LANMailServer allows sending and receiving emails within a local network, requiring only one computer with internet access. Using a conventional email program that supports the POP3/IMAP4 and SMTP standards, emails can be received and sent. It supports normal text emails, HTML format emails with or without file attachments. LANMailServer can be used with LAN connections and dial-up connections (Dial-Up Networking, T-Online Software).

Overview of Features

• Windows service that runs in the background without requiring a Windows user login. Server configuration is done via the LANMailServer Console software.

• Creation of local email accounts, including options for forwarding emails locally or to the internet, and an autoresponder function. (Shareware version supports up to 2 email accounts, with no forwarding options or autoresponder features.)

• Creation of email groups to consolidate email accounts, allowing emails to be sent directly to the group rather than to individual recipients.

• Emails can be sent within the network and to internet.

• Emails from external email accounts can be retrieved and assigned to local users. External email accounts supporting POP3/IMAP4 standards are supported. (Shareware version supports up to 2 external email accounts.)

• Sending emails of any size within the network or to the internet using the integrated SMTP server or any SMTP server of an email provider (Shareware version restricts email size to max. 100 KB).

• Sending emails via HTTP from webspace or a personal server using the included PHP script, via Microsoft 365/Microsoft Graph (maximum email size: 3.9 MB), or via Amazon SES (maximum email size: 10 MB).

• Retrieval of emails from local email accounts via POP3 or IMAP4.

• The IMAP4 server supports IMAP4rev1 with extensions UIDPLUS, MOVE, IDLE, APPENDLIMIT, and NAMESPACE.

• Modern authentication with OAuth2 support for Microsoft Office 365/Exchange online accounts, and optionally for Google Mail after setting up a custom app.

• Security for receiving emails by restricting reception to the local PC or a definable IP address range.

• Security for sending emails by restricting transmission to the local PC or a definable IP address range.

• Logging functionality to document server access.

• Viewing existing server connections.

• Viewing emails in the outgoing queue with options to check info on delivery issues or delete emails from the outgoing queue.

• SMS notifications for new email arrivals (requires registration with SMSout.de service, Germany, Austria and Switzerland only).

• Local mailboxes can be designated as e-invoice mailboxes. Incoming emails are checked for attachments in XML format (ZUGFeRD DIN EN16931 or XRechnung) or PDF format (PDF/A with attachments in XML format). Detected e-invoices can be forwarded to another email address or retained in the mailbox.

System Requirements

• Operating system: Windows 7 or newer versions, and Windows Server 2008 or newer versions.

• At least 100 MB of hard drive space; additional space may be needed for email storage.

• Screen resolution of at least 256 colors (recommended: 16 million colors) at a minimum of 800x600.

• POP3 and/or IMAP4-capable email program (e.g., Microsoft Outlook, Windows Live Mail, Thunderbird, eM Client, The Bat!).

• For receiving external emails or sending emails to external addresses: an email provider with at least one POP3/IMAP mailbox and/or SMTP server for email transmission.

• For accessing MySQL databases: Microsoft Visual C++ 2013 runtime. If necessary DLLs are not available on the system, a notification will appear during database access.

LANMailServer consists of a Windows service, the server application, and the LANMailServer Console program for administering server application. You can log off from the computer without any issues—LANMailServer will continue to run in the background, handling all incoming and outgoing emails. It is also not necessary to have the LANMailServer Console software running permanently.

LANMailServer is ready to use immediately after the first launch; you only need to:

• Complete the program configuration,

• Set up local email accounts,

• Set up any necessary groups, and

• Configure a POP3-/IMAP4-capable email program.

See also:  Settings of LANMailServer

General

Local Email Accounts

Internet Connection

POP3 Server

IMAP4 Server

SMTP Server

Autoresponder

If the autoresponder has been enabled for local email accounts, the following options influence the autoresponder function.

SMS Sending (only for Germany, Austria, and Switzerland)

To send SMS messages for incoming emails, you need to register with the SMS service SMSout.de. The SMS is sent using the HTTP protocol, and encrypted transmission (HTTPS) can also be used.
For each local email account, you can individually enable SMS sending and specify a mobile number.

Appearance

Define the style in which the LANMailServer Console program interface should be displayed. After changing the style, the LANMailServer Console should be closed and restarted.

Advanced

Internal Settings

SSL Certificate

HTTP API/OAuth2 Server

The HTTP server is used to implement the JSON API for creating, deleting, and modifying users. Additionally, the HTTP server supports OAuth2 authentication if the email program allows configuration of custom apps.

JSON API Commands

OAuth2 Endpoints and Parameters

ClamAV

ClamWin and clamd must be installed on your computer.

Using ClamAV/ClamWin/Clamd with LANMailServer

Language

Select the language of the program interface and messages displayed on screen and in the log file. After changing the language, you must restart the LANMailServer service to ensure the service outputs log messages in the selected language.

Notes on SSL Access

For SSL access, LANMailServer includes its own self-signed certificate for the server name "localhost." If the email program or antivirus software issues a warning during SSL-secured access, this certificate must be added to the Windows certificate store. To install the certificate, follow these steps:

1. Press Windows key and R to display the Windows Run dialog.
2. Enter certmgr.msc in the Run dialog and click OK.
3. In the certificate manager, select Trusted Root Certification Authorities and then Certificates on the left.
4. Under the Action menu - All Actions, select Import.
5. Select the certificate lanmailserver.crt in the LANMailServer program folder and let it be imported.

Click on "Local Email Accounts" under Configuration to open the dialog for managing local email accounts.

For each user, a local email account should be set up. It is also possible to retrieve emails from external mailboxes for each email account and assign them directly to each user. This enables the sending/receiving of emails within the local network or sending emails to the internet. When setting up the email account, enter the username without spaces, special characters, or umlauts. After setting up the account, an email can be sent directly to <username>@<domainname> from an email program on the LANMailServer PC. In the recipient's email program, a corresponding email account must also be configured. Specify the name of the PC running LANMailServer as the incoming mail server (POP3 or IMAP4). Use the username and password you provided when creating the email account in LANMailServer as the account name (username) and password.

To create a new email account, click on "Add." To modify an existing account, select the email account from the list and click on "Edit." To delete an email account, select the account and click on "Delete."

In the Shareware version, a maximum of 2 local email accounts can be created.

See Also:

• Settings for local email accounts

• Retrieving emails from external mailboxes

• Setting up groups

• Using the email archive

Click on "Local Email Accounts" in the Configuration menu to create, modify, or delete new local mailboxes.

To create a new email account, click "Add." To modify an existing account, select the email account in the list and click "Modify." To delete an email account, select the account and click "Delete."

In the Shareware version, a maximum of 2 local email accounts can be created.

In custom applications/scripts, email accounts can be created or modified via the JSON API.

General Tab

Autoresponder Tab

Using the autoresponder, you can automatically send a reply email to the sender of an email. As soon as LANMailServer receives an email in the local email account, including from external email accounts, LANMailServer automatically sends an email with the specified text.

External Accounts Tab

On this tab, you can specify external email accounts, i.e., email accounts hosted by an email provider. These email accounts are regularly checked by LANMailServer (see Configuration Menu - Program Configuration under Local Email Accounts) for new incoming emails. Emails are retrieved and then transferred to the local email mailbox so that they can be accessed and responded to like local emails.

Outgoing Mail Tab

On this tab, choose whether the settings from the program preferences for sending emails to the internet should be used. A different SMTP server or a different username for SMTP authentication can be specified, or alternatively, emails can be stored in a local folder, uploaded via HTTP POST to a web server, or sent via a PHP script through a web server.

Alternative SMTP Server

Save in a Folder

Instead of sending emails via SMTP, emails can be stored in a local folder and used by custom software. Adequate storage space must be available; if saving fails, the email will be considered not sent, and further attempts to save will be made.

Transmit via HTTP Post

Sends emails via HTTP Post to a custom script or software running on a web server. A variable name must be specified, and the custom script or software must evaluate this variable. The email is considered sent if HTTP error code 200 is returned. Other error codes result in a repeated upload via HTTP POST.

Note: To store data in a local folder, it is recommended to save directly to the folder, as this reduces unnecessary overhead.

Example PHP script for accepting the data and saving it in a directory:

 function SetHTTPResponseCode($httpStatusCode, $httpStatusMsg){
   if($httpStatusCode > 0){
       $phpSapiName    = substr(php_sapi_name(), 0, 3);
       if ($phpSapiName == 'cgi' || $phpSapiName == 'fpm') {
          @header('Status: '.$httpStatusCode.' '.$httpStatusMsg);
       } else {
          $protocol = isset($_SERVER['SERVER_PROTOCOL']) ? 
                            $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.0';
          @header($protocol.' '.$httpStatusCode.' '.$httpStatusMsg);
       }
   }
 }

 $UploadVar = 'rfc822data';
 $DestPath = 'd:/xampp/'; // Save folder

 if(isset($_FILES[$UploadVar])){
   $target_file = $DestPath  .  basename($_FILES[$UploadVar]['name']);
   if(!move_uploaded_file(
      $_FILES[$UploadVar]['tmp_name'], $target_file)){
     SetHTTPResponseCode(500, 'Can't save to ' . $target_file);
   }else
     SetHTTPResponseCode(200, 'OK');
 }else{
  SetHTTPResponseCode(403, $UploadVar . ' not found.');
 }
    

Transmit via Webspace/Own Server

Emails are sent via HTTP POST to a provided PHP script, which then sends the email to the recipient. PHP5 or newer is required.

Note: Due to the overhead of the HTTP protocol, this method should only be used if sending emails via SMTP in your own network is not possible.

Click on "Perform Upload of PHP Scripts" to transfer the scripts via FTP/SFTP to the webspace. The script call will be tested in the process; in the event of an error, the directory on the webspace or the HTTP(s) call must be corrected. Providing the script password is necessary to secure the script call; the password should be very long.

Note: The scripts must not be deleted or moved on the webspace. You can always re-upload the scripts to the webspace by clicking "Perform Upload of PHP Scripts" and carrying out the upload.

The script on the webspace will send emails using PHP mail() (default). Alternatively, you can specify an SMTP server with SMTP authentication to send emails via this SMTP server.

When LANMailServer is to send an email, the email is transferred as a file via FTP/SFTP, after which this file is sent via a script call. Sending is therefore not possible through a simple HTTP(s) call of the script, even with knowledge of the script password.

Via HTTP using Microsoft Cloud (Microsoft/Office 365)

Emails are sent to Microsoft servers via the HTTP protocol using the Microsoft Graph API. A sender email address must be provided prior to sending, followed by the retrieval of an access token. All sender addresses of outgoing emails will be replaced by this email address, as Microsoft only allows sending emails using authorized addresses.

Notes

• Before retrieving the token, the correct account type must be selected:

  • Work or School Account These accounts are managed by Microsoft for organizations using Azure Active Directory. They are used to sign in to Microsoft (Office) 365 and other enterprise services.

  • Personal Account (formerly Windows Live ID) These accounts represent individual relationships with Microsoft and are used to access consumer devices and services. They are intended for personal use.

• Maximum email size is 3.9 MB; Microsoft servers do not allow larger messages.

• It is always recommended to send emails via SMTP server smtp.office365.com as HTTP-based sending is much slower.

• If an HTTP proxy server is required, it must be specified in the application’s internet connection settings.

• An access token must always be retrieved. The service cannot obtain tokens without user interaction but can renew existing ones.

• If no emails are sent with the token for more than 6 months, the Microsoft server declares it invalid and a new token must be retrieved.

Via HTTP using Amazon SES

You must register with Amazon SES and independently configure all settings for your domain and sender email address. Afterwards, apply to switch to production mode with Amazon SES.

Amazon SES supports sending via SMTP server, which you should also use with LANMailServer. If sending via SMTP is not possible (e.g., blocked ports by a company firewall), you can use this method to send emails via HTTP API through LANMailServer. Keep in mind, HTTP sending is slower than SMTP.

Configuration

• Create an SMTP user in Amazon SES. You will receive a username and password.

• Use the username as AWS Access Key and the password as AWS Secret Key.

• Choose the correct AWS region that Amazon has approved for you.

• Enter in LANMailServer the sender email address registered in Amazon SES. LANMailServer will replace the sender on all outgoing emails with this address. Sending from unauthorized or arbitrary email addresses is not allowed in Amazon SES.

Limits

• Maximum email size: 10 MB

• Maximum recipients (To/Cc/Bcc): 50 per email

• Do not exceed Amazon SES’s per-minute sending limit. Avoid sending mass emails directly through SES. Instead, use newsletter software like SuperMailerto comply with rate limits.

OAuth2 Clients Tab

You can create one or more OAuth2 clients for each local email account to enable OAuth2 authentication, provided the email program allows configurable endpoints. Client IDs and client secrets are automatically and uniquely generated and cannot be modified. Using the access scope, you can restrict later access via POP3, IMAP, or SMTP. With the "Copy URLs" function, you can directly copy the endpoints. In the program settings, the HTTP-API/OAuth2 server must be activated; otherwise, OAuth2 authentication will not be available.

OAuth2 Endpoints and Parameters

See Also

Query Emails in External Mailboxes

LANMailServer Settings

Specifying external mailboxes is only necessary if the email account owner also has external email accounts with an email provider on the internet. LANMailServer retrieves emails from the external mailboxes and assigns them to the local email account. This allows the user to receive, read, reply to, and send emails locally. LANMailServer supports email accounts that conform to the POP3/IMAP4 standard, additionally supporting Hotmail and AOL accounts.

If emails from external mailboxes are to be integrated into multiple local email accounts, the global external mailboxes should be used.

In the Shareware version, a maximum of 2 external email accounts can be created for each local email account.

Import Button for Email Accounts

Using the import wizard, you can import email accounts from Microsoft Outlook or Microsoft Outlook Express on the local computer. AOL mailboxes cannot be imported.

Important

• LANMailServer cannot read passwords for email accounts; you must enter these passwords in the import wizard.
• For importing from Outlook, LANMailServer must be used as the 32-bit version if Outlook is installed as a 32-bit version, otherwise use the 64-bit version.

Setting Up External Email Accounts

You can add, modify, and delete external email accounts. All accounts that are added and checked will be monitored by LANMailServer for incoming new emails. If emails are present, they will be retrieved, assigned to the local email account, and then deleted from the external email account.

Add, Modify, and Delete Email Accounts

Click "Add" to include a new external email account in the software. To modify an email account, select the email account from the list and click "Modify." To delete an account, select the account and then click "Delete."

See Also

Add/Modify a POP3 Account
Add/Modify an IMAP Account

By creating groups, you can consolidate multiple local email accounts. For example, you can create a marketing group and a sales group and assign local email accounts to them. If you want to send an email to a group, you don't need to specify each email recipient individually. Instead, you can, for example, send an email to sales@<domainname> to email all the accounts in the Sales group.

Notes:

• Only local email accounts can be assigned to a group.

• Local email groups are only accessible within the network. Emails from the internet cannot be sent to local groups.

To create a new group, click "Add." To modify an existing group, select the group from the list and click "Modify." To delete a group, select the group and then click "Delete."

Settings for Local Email Groups

General Tab

Enter a unique name for the group. The group name must not contain spaces, special characters, or umlauts. This name will also form the part before the "@" symbol when you later send an email to the group members.

Group Members Tab

On this tab, specify local email accounts to be part of the group. Click "Add" to see all local email accounts and select the accounts to include. To remove an account from the group, select it from the list and click "Delete."

See Also:

Set up local email accounts

Click "Test Settings" to test the inbox settings.

See Also

Retrieve Emails from External Mailboxes

Settings for Global External Email Accounts

Inbox Tab

Click "Test Settings" to test the inbox settings.

See Also

Retrieve Emails from External Mailboxes

Settings for Global External Email Accounts

Global external mailboxes can be used to distribute emails from one or more external mailboxes to the local mailboxes in LANMailServer.

Click on "Global External Mailboxes..." under Configuration to create, modify, or delete new external mailboxes.

To create a new email account, click "Add." To modify an existing account, select the email account from the list and click "Modify." To delete an email account, select the account and click "Delete."

Inbox Tab

Add the respective mailbox:

Add a POP3 Account
Add an IMAP Account

Email Distribution Tab

Note: If you delete local mailboxes that were specified on the Email Distribution tab, the retrieval of the external mailbox will no longer be performed. You must first revisit the settings of the external mailbox, check the configuration, and save it.

See also

LANMailServer Settings

OAuth2 is currently supported by Microsoft Office 365/Exchange Online and Gmail. Other providers/applications that also support the OAuth2 standard can be configured independently, e.g., LANMailServer Email Server.

Difference Between BASIC/Standard Authentication and "Modern Authentication" OAuth2

The POP3, IMAP, and SMTP protocols provide authentication using a username/email address and password. Over the years, various simple and complex encryption methods have been developed to ensure that login credentials cannot be intercepted during client-server communication.
With "Modern Authentication" using OAuth2, permission from the user must be obtained via a browser using an additional app provided by the server operator. Once permission is granted, the application receives an access token. Authentication then occurs using this token without transmitting the password. The access token expires at short intervals, requiring a new one to be requested repeatedly. This is more secure than using the same password continuously.
Disadvantage of "Modern Authentication": A separate app must be created for each server operator, and proof of authenticity may be required, making this process time-consuming.

Information about OAuth: Wikipedia OAuth

Built-In OAuth2 App

An app is pre-integrated for accessing Microsoft accounts. You need to select the correct account type to gain access.

For Google accounts, you must create an app yourself due to the complex verification process: Create OAuth2 App in Google Cloud.

Newsletter SuperMailer: Import contacts from Microsoft Cloud or send emails via Microsoft Cloud.

This functionality uses a separate app with its own access tokens, which must be authorized separately.

Using OAuth2

In the respective dialog for sending or receiving emails, choose:

<SMTP/POP3/IMAP> AUTHentication Basic/Standard

OAuth2 <account type> or

OAuth2 <custom_app>.

You do not need to enter a password.

Then click on the "Test" button to authorize the app in the browser (authorization) and obtain an access token for the desktop program.

Using the Access Token

The desktop program will use the access token instead of the password in the future and will also update it automatically every 60 minutes. This access token will be used for the SMTP, POP3, and IMAP protocols for the respective email address when OAuth2 is selected for authentication.

Data Storage

The desktop programs SuperMailer, BirthdayMailer, FollowUpMailer, MailboxFetcher, and SuperSpamKiller Pro store the data encrypted in the Windows registry. All desktop programs access the same data, so it is not necessary to authorize access or create a new app in every desktop program.

The LANMailServer email server uses its own app and stores the data in the local database, allowing easy data transfer when moving the server.

Adding Custom OAuth2 Apps or Deleting Access Tokens

In the desktop program for configuring email sending or receiving, select "Manage OAuth2 Apps and Tokens."

See Also

OAuth2 App for Accessing Microsoft Accounts for SuperMailer, BirthdayMailer, FollowUpMailer, MailboxFetcher, and SuperSpamKiller Pro

OAuth2 App for Accessing Microsoft Accounts for LANMailServer

Create OAuth2 App in Microsoft Cloud for Office 365/Exchange Online

Create OAuth2 App in Google Cloud

In the email archive, all incoming and outgoing emails can be archived. LANMailServer stores the emails in a local database, which can be searched based on specific criteria. It is not possible to display all archived emails at once due to the potentially large volume of data.

To use the email archive, the checkbox "Archive all incoming/outgoing emails for this email account" must be selected for the respective local email account. Emails are only archived under this condition.

Emails in Email Archive

Click into the search field and enter a search term to look for it in the sender, subject, or recipient name, then press the <ENTER> key. Alternatively, click on the small arrow of the search button and select "Advanced Search," or use the "Advanced Search" button.

To change the sorting of columns or to add more columns, click "Columns...".

To view an email, select an email from the search results and click "View" to display it in the internal viewer.

If you want to permanently delete one or more emails from the archive, select the email(s) and click "Delete Email."

To save an email, select it and click "Save."

In the LANMailServer settings, you can find the data folder, which is usually located at c:\ProgramData\LANMailServer. All data in this data folder must be backed up. Before performing the backup, the LANMailServer service must be stopped to ensure the email database is fully written to the storage device.

Restoring the Backup

All data must be restored to the data folder. Naturally, the LANMailServer service must be stopped beforehand.

If the data is stored in a MySQL database, the MySQL database must also be backed up/restored.

Starting and Stopping the Service

Through Control Panel - Administration - Services, you can stop and restart the LANMailServer service.

Using the Command Prompt...

Open the Command Prompt with administrator rights and enter:

net stop LMService

To start the service:

net start LMService

See Also

Move LANMailServer to another Computer

In the LANMailServer settings, you can find the data folder, which is usually located at c:\ProgramData\LANMailServer. All data in this folder must be transferred to the new computer. This data contains the entire configuration.

Performing migration

• Log in as an administrator on both the old and the new computer.
• First, stop the LANMailServer Service
• Copy all data from the data folder to the new computer, or transfer it via an external hard drive/NAS drive/cloud drive/network drive and then onto the new computer.
• Uninstall LANMailServer on the old computer (Control Panel - Programs and Features - Uninstall LANMailServer).
• Install LANMailServer on the new computer.

After installation, LANMailServer will start and access the existing data. Start the LANMailServer Console and re-enter the license, as this is necessary to access all users.

Starting and Stopping the Service

Via Control Panel - Administration - Services, you can stop and restart the LANMailServer Service.

Using the Command Prompt...

Open the Command Prompt with administrator rights and enter:

net stop LMService

To start the service:

net start LMService

See Also

Perform a Backup

To send and receive emails, any email program that supports the POP3 and/or IMAP4 standard for receiving emails and the SMTP standard with authentication (SMTP Auth) can be used.

General Settings for any email program (Outlook, Thunderbird, eM Client...)

For Receiving Emails

Email Address: Email address of the local email account
Incoming Mail Server: localhost, if LANMailServer runs on your own computer; otherwise, name orIP address of thecomputer where LANMailServer is running

For POP3 Port: 110 (unless this was changed in the program configuration)

For IMAP4 Port: 143 (unless this was changed in the program configuration)

For Sending Emails Through Email Programs, Scripts, Print Servers...

Outgoing Mail Server: localhost, if LANMailServer runs on your own computer; otherwise, name or IP address of the computer where LANMailServer is running

Port: 25 (unless this was changed in the program configuration)

Sending emails is only possible with SMTP authentication. If the email program supports the option "Use the same credentials as for incoming mail," you can activate the corresponding option in the email program. If this function is not supported, you must enter the username and password for a local email account.
If you use an SMTP server from the email provider to send emails to the internet, you need to configure the SMTP server of the email provider and the username and password for SMTP authentication with the email provider in the LANMailServer settings.

Setup with Thunderbird

In Thunderbird settings click on "New Account"  and add a new Mail Account.

Enter your full name, Email address and Password for accessing local LANMailServer email account.

Click on "Configure manually", to enter Inbox/Outbox hostname.

Enter as hostname for incoming/outgoing server localhost, when LANMailServer is installed on same computer or name/IP address of computer with installed LANMailServer.

Click on "Re-test" to test your settings. When all settings are correct, click on "Done".

Now you can use Thunderbird to retrieve emails/send emails from/to LANMailServer.

See Also

LANMailServer with Outlook and Windows (live) Mail (german)

LANMailServer Settings

Settings for Local Email Accounts

Set up Groups

Issues When Using LANMailServer

How Can I Get Help with LANMailServer?

Visit the Support Forum to search for an answer to your question or ask your question directly in the forum.

LANMailServer Console Cannot Connect to the Windows Service...

Ensure the Windows service "LANMailServer Service" is running on the same computer as LANMailServer Console. Also check the Windows Event Log, as Windows services cannot directly display error messages. You can view the Windows Event Log via Control Panel - Administration.

I Keep Receiving a Socket Error in the Windows Event Log on Startup...

This error may have two causes:

1. Check the port settings in the LANMailServer Console under Configuration - Settings - POP3/IMAP4 Server. If you are already using another POP3/IMAP4 server, set the LANMailServer POP3/IMAP4 server to a different port. Don't forget to update the port in your email program.
2. If you're using a firewall, check whether it allows internet access through LANMailServer (Ports 25, 53, 80, 110, 143).

Problems with Antivirus Software

Disable the antivirus software or outgoing email scanning before sending emails to avoid issues with email delivery. This problem typically occurs when sending a large number or large-sized emails.

Checking Incoming Emails for Viruses

LANMailServer does not have interfaces for antivirus programs. If your antivirus program supports it, you can configure it to scan the "ScanMail" folder under the specified data folder (as set in the LANMailServer Console configuration). The antivirus program should delete infected emails from the folder, after which LANMailServer will ignore these emails.

I Receive the "Permission Denied" Message or Another Error When Retrieving Emails in the Email Program

Check the settings for the email account in your email program. Make sure the username (account name) and password are correctly entered. Also verify the access restriction settings in the LANMailServer Console under Configuration - Settings - POP3/IMAP4 Server.

Errors Occur When Sending Emails

1. Check your firewall settings.
2. Verify the settings in the LANMailServer Console under Configuration - Settings - SMTP Server, including the username and password for email sending.
3. Ensure the data folder is correctly specified in the LANMailServer Console under Configuration - Settings - General, and that LANMailServer has read/write permissions for this folder. The folder is usually c:\programdata\lanmailserver, and the System and Administrator users must have full access. Users must be able to read, execute, write, modify, and view folder contents.

When Receiving Emails, the Message "Forbidden: Your client is not allowed to access the POP3 server." or "Forbidden: Your client is not allowed to access the IMAP4 server." Appears

Check the access restriction settings in the LANMailServer Console under Configuration - POP3/IMAP4 Server.

When Sending Emails, the Message "550 Forbidden: Your client is not allowed to access the SMTP server." Appears

Verify the access restriction settings in the LANMailServer Console under Configuration - SMTP Server.

When Sending Emails, the Message "Relaying Denied, Use SMTP Auth" Appears

SMTP authentication is not enabled in your email program, or the username and password for SMTP authentication are incorrect.

When Sending Emails, Error 354 Appears: "Start Mail Input; End with . Exception: Attached File Not Found or Access Denied."

Check the internet connection to ensure it is not blocked by anonymization programs or firewalls.

When Sending Emails, Error 421 Appears: "<domain> Service Not Available, Closing Transmission Channel."

The SMTP server cannot resolve more domain names into IP addresses because the service responsible for this data resolution is not accepting additional requests. This may have two causes:

• A technical issue with the SMTP server; only the email provider can resolve this.
• No internet connection exists, or a firewall is blocking access to the DNS service (Port 53).

When Sending Emails, Error 500 or 501 Appears: "Syntax Error"

1. Check the spelling of your email address for the email account in your email program.
2. Verify your computer name; it must not contain spaces, special characters, or umlauts.
   On Windows 7 and newer: To change the computer name, click System in the Control Panel. Go to the Computer Name tab and click Change. Other operating systems have similar steps.

When Sending Emails, Error 530 Appears: "Authentication Required."

SMTP authentication is not enabled. Enable authentication for the SMTP server in your email program and enter a valid username and password. If you are using the SMTP server of your email provider, enter the username and password for the provider's SMTP server in your email program. You must also enter the same credentials in the LANMailServer Console under Configuration - Settings - SMTP Server.

When Sending Emails, Error 550 Appears: "Requested Action Not Taken: Mailbox Unavailable."

This error is returned by the SMTP server when the recipient's mailbox does not exist, indicating the email address is invalid.

When Sending Emails, Error 552 Appears: "Requested Mail Action Aborted: Exceeded Storage Allocation."

The SMTP server has insufficient space to temporarily store the email. LANMailServer will continue attempting to send the email until space becomes available. You can also inform your email provider to resolve the issue promptly.

Additional SMTP Error Codes

LANMailServer itself provides the capability for an email program or script to authenticate using OAuth2 to retrieve and/or send emails.

In the program settings, the HTTP-API/OAuth2 server must be enabled; otherwise, OAuth2 authentication will not be available.

The documentation assumes that the HTTP-API/OAuth2 server is running on HTTP Port 6080.

All HTTP-GET parameters must be URL-encoded.

If there is no access using the token for 6 months, it will be deleted, and a new browser authentication will be required.

Authorization endpoint, retrieve access code

Example URL

The URL must be accessed in a browser, and the username and password must be entered correctly.

Example Response

The provided redirect_uri is returned with the parameters code= and, if specified, state=<value>.

http://localhost/oauth2/code?state=state_parameter_passthrough_value&code=<CODE>

If errors occur, they are displayed directly in the browser, e.g., parameter_error; client_id doesn't exist or is disabled.

AccessToken endpoint, exchange code for access token

The exchange must take place within 30 seconds; otherwise, the code will expire.

Example URL

Example Response (JSON)

{ "access_token": "1/abcedefghij", "expires_in": 3920, "token_type": "Bearer", "scope": "IMAP.AccessAsUser.All SMTP.Send", "refresh_token": "1/stuvwxyz" }

If errors occur, the parameters error= and error_description= are returned via redirection.

http://localhost/oauth2/code?error=<errorcode>&error_description=<errortext>

RefreshToken endpoint, updating access token

Every 60 minutes the access token expires, and a new access token and refresh token must be retrieved using the refresh token.

Example URL

Example Response (JSON)

{ "access_token": "NEU_1/abcedefghij", "expires_in": 3920, "token_type": "Bearer", "scope": "IMAP.AccessAsUser.All SMTP.Send", "refresh_token": "NEU_1/stuvwxyz" }

If errors occur a JSON array with parameters error= and error_description= are returned.

{ "error": "<errorcode>", "error_description": "<errortext>" }

Logout

Example URL

Response

HTTP error 200 will be returned.

If errors occur a JSON array with parameters error= and error_description= are returned.

{ "error": "<errorcode>", "error_description": "<errortext>" }

In an email program, the server name for POP3/IMAP and SMTP is entered. When accessing via SSL, the server name must match the name in the SSL certificate; otherwise, the error "Target principal name is incorrect" will be displayed during access. LANMailServer is installed on a regular Windows computer (workstation or server), and this Windows computer has a name that can be used as the server name within the network. The SSL certificate must be issued for the server name to avoid errors in the email program.

Create Your Own SSL Certificate

Windows software OpenSSL is required to create the certificate. You can download the 32-bit or 64-bit Windows version from https://slproweb.com/products/Win32OpenSSL.html and then install it. It's best to install the software directly into C:\OpenSSL, D:\OpenSSL, etc., as the software is a console application without a graphical user interface, making it easier to navigate to the folder via the console. In this example, the software was installed to E:\OpenSSL-Win32.

• Create a folder named "lanmailserver" in Windows Explorer, preferably directly in the root directory of drive C:, D:, E:, etc., as this saves time when typing.
• Open the Command Prompt, navigate to the drive where OpenSSL is installed, then to the OpenSSL installation folder, and then to the bin subfolder.
• Enter:
  
  openssl req -new -days 9999 -newkey rsa:4096bits -sha512 -x509 -nodes -passin pass:<password> -passout pass:<password> -out <drive>:\lanmailserver\lanmailserver.crt -keyout <drive>:\lanmailserver\lanmailserver.pem
  
  Replace <password> with a password without spaces, avoiding special characters or umlauts. Both passwords must be the same.
  Replace <drive> with the drive containing the "lanmailserver" folder.
  
  The -days parameter was set to 9999 so the certificate will be valid for 9999 days. If fewer days are specified, a new certificate will need to be created after expiration.
  
  
  
• Press ENTER to begin generating a private key.
• You will be prompted for various information. The most important detail is " Common Name (e.g. server FQDN or YOUR name)," where the correct email server name must be entered. This is the name that must later be entered in the email program. All other information can be provided, but avoid umlauts and special characters. Simply press ENTER/RETURN to accept default values.
• Type "Exit" to close the Command Prompt.
• In the LANMailServer settings, select the option for a custom SSL certificate, choose the files lanmailserver.crt and lanmailserver.pem located in <drive>:\lanmailserver, and enter the <password>. The files and folder <drive>:\lanmailserver must not be deleted.
  
  

Adding the Certificate to Trusted Root Certificates

1. Press the Windows Key + R to open the Windows Run dialog.
2. Type certmgr.msc in the Run dialog and click OK.
3. In the Certificate Manager, select Trusted Root Certification Authorities and then Certificates on the left.
4. Under the Action menu, select Import.
5. Select the certificate lanmailserver.crt from the folder <drive>:\lanmailserver and let it import.
6. On each computer that requires SSL access to LANMailServer, importing into Trusted Root Certificates may be necessary.

Simple Example: For the server name lanmailserver.de, OpenSSL was installed on drive E:\OpenSSL-Win32, and the password used is "GEHEIM":

In the email program, lanmailserver.de must be entered as the POP3 or IMAP4 and SMTP server for this example. Only this name can be used with the SSL certificate. If the server name is not correctly entered, the email program will display the error "Target principal name is incorrect."

Settings in LANMailServer:

In Windows Explorer, you can directly click on the file lanmailserver.crt to view details about the server name and validity.

In LANMailServer settings, you can enable email scanning with ClamAV. To do this, you must install ClamAV.

You need to download and install the software yourself, which requires administrator rights and basic Windows/DOS knowledge.

Install ClamAV

Download the latest version of ClamAV for Windows from https://www.clamav.net/downloads and install it on the computer where LANMailServer is installed.

Do not start ClamAV after installation is complete.

ClamAV Folder

ClamAV is installed to:

• 32bit version: C:\Program Files (x86)\ClamAV
• 64bit version: C:\Program Files\ClamAV

Configuration for clamd and freshclam

To run ClamAV as a service, clamd is required. LANMailServer passes the email to clamd via port 3310, which scans it for viruses and returns a result: infected/not infected.

Configuration files for clamd and freshclam are required. You can download them ready-made:

Download conf files

Administrator rights required: Unzip the ZIP file and copy clamd.conf and freshclam.conf into the ClamAV folder.

If you want to make changes to the conf files yourself, open them in Notepad and edit them. Then save the file in Windows ANSI format, not in UTF-8 format, which is now the default in Notepad.

Create additional folders manually

clamd and freshclam require additional folders that you must manually create.

Open Windows Explorer on drive C:\ and go to the ProgramData folder. If the folder is not visible, you must enable hidden folders in Windows Explorer or manually enter C:\ProgramData in the address bar and press RETURN/ENTER.

Create the folder .clamwin in C:\ProgramData, and within it the folders db and log, so that the following folders exist:

C:\ProgramData\.clamwin\db
C:\ProgramData\.clamwin\log

Install clamd and freshclam as services and update ClamAV database

clamd must run as a background service so that no user needs to be logged in. freshclam must also run to download virus database updates every 12 hours.

Start Command Prompt or PowerShell as Administrator.

Navigate to the ClamAV folder

32bit: cd %ProgramFiles(x86)%\ClamAV

64bit: cd %ProgramFiles%\ClamAV

Type and press RETURN/ENTER:

clamd --install-service

then

freshclam --install-service

Now perform a download of the virus database by typing:

freshclam

and pressing RETURN/ENTER.

This will download the ClamAV databases. If errors occur, they will be displayed and must be resolved.

Start clamd and freshclam as services

Type and press RETURN/ENTER:

net start clamd

to start clamd,

net start freshclam

to start freshclam and allow it to check for virus database updates every 12 hours.

net stop clamd and net stop freshclam can be used to stop the services. Alternatively, in Control Panel - Administrative Tools - Services, you will find "ClamAV ClamD" and "ClamAV FreshClam" in the list of running services and can stop or start them there.

ClamAV Documentation

Maximum size of emails to be scanned

The clamd service supports files up to 25 MB. If larger emails need to be scanned, add StreamMaxLength with a size in megabytes to the end of clamd.conf, e.g. 30 MB:

StreamMaxLength 30M

Be sure to save in Windows ANSI format. You must stop and restart the clamd service after changes to the conf file.

Updates

The virus databases are automatically updated by freshclam, but ClamAV itself is not. For updates, you must download the new version of ClamAV, uninstall the old version, and install the new one.

You can easily install a MySQL server on your own computer or any computer within your network. When using it with LANMailServer, it is recommended to install the database on the same computer to avoid delays caused by the network itself.

MySQL 8.0 or MariaDB 10.2 or newer is required. Older versions of MySQL/MariaDB cannot be used because SQL Window Functions are not supported by older versions.

For MySQL/MariaDB Experts

The latest MySQL server version can be found at https://dev.mysql.com/downloads/ or for MariaDB server at https://mariadb.org/. You must manage the configuration of the databases and database users yourself.

Example of manually creating a user named lanmailserver with the password lanmailserver_is_super, allowing access from all hosts.

A mail filter, or Milter for short, is used to process incoming emails. Such Milters are used by Sendmail and Postfix. In LANMailServer, custom Milters can be created in the form of DLLs, allowing incoming emails received via SMTP to be modified or completely discarded. Emails retrieved from external mailboxes cannot be modified.

The service "LANMailServer Milter Service" is invoked locally by LANMailServer via TCP/IP with the respective email data. The Milter Service forwards the data to the defined Milter DLLs. The Milter Service is executed in its own memory space, separate from the LANMailServer Service.

File lmsmilters.ini

Custom Milter DLLs must be added to the file lmsmilters.ini with their drive, folder, and filename in the [MilterLibs] section with unique keys. The file lmsmilters.ini is always searched for in the LANMailServer program folder.

Example

[MilterLibs]
0=C:\Milters\MilterDLLTest.dll
1=C:\Milters\MilterTestDLL.dll

Create Your Own Milter DLL

Important: The custom Milter DLL must be compiled in 32-bit if LANMailServer is used as a 32-bit application; otherwise, it must be a 64-bit DLL.

Example for a Delphi DLL in the LANMailServer program folder file MilterDLLTest.dpr.

All strings are defined with the C++ data type BStr. Strings are initialized using the Ole2 function SysAllocString and released with SysFreeString. If assigning a custom string, the memory of the passed string must be freed using SysFreeString, then reinitialized with SysAllocString. The service will handle the release afterward.

The data type DWORD corresponds to Cardinal or longlong.

The calling convention is always stdcall, not cdecl!

The custom DLL must always export the procedure MilterInformation().

The callback functions are called during the email client-to-server connection. If the response takes too long, the client will display an error message and disconnect. The callback functions should respond quickly to avoid disconnections. The Milter Service waits a maximum of 60 seconds for a response; otherwise, it always returns MilterTempfail.

Return Values of Callback Functions

MilterOK = 0x1; MilterDenied = 0x2; MilterTempfail = 0x3; 
MilterAccept = 0x1000; MilterReject = MilterAccept + 1; 
MilterContinue = MilterReject + 1 
    
    
    
    
    

Procedure to Export

procedure MilterInformation(var MilterName: BStr; 
      
      
MilterVersion: PDWORD); 
    
    
    
 
    
    

This procedure tests the validity of the DLL; the return values are not evaluated.

Pointer to BSTR MilterName returns an identifier for the Milter using the Ole2 function SysAllocString. The Milter Service releases the string using SysFreeString.

Pointer to DWORD MilterVersion can return a version.

Optional Functions to Manipulate Email Content

function callback_envfrom(const SessionHandle: DWORD; 
var mailFrom: BStr): DWORD; 
    
    
    

Executed after the SMTP command MAIL FROM:. Envelope sender is passed.

Unique SessionHandle is passed as a DWORD.

Pointer to BSTR mailFrom, the envelope mail from is passed and can be modified. To modify, release the string with SysFreeString and initialize a new string with SysAllocString.

Return Values

MilterAccept or MilterContinue => Envelope mail from is accepted, and any changes are applied

MilterDenied or MilterReject => Envelope mail from is not accepted => Email is rejected by the server

MilterTempfail => Milter error, email is accepted

function callback_envrcpt(const SessionHandle: DWORD; 
var mailRcpt: BStr): DWORD; 
    
    
    

Executed after the SMTP command RCPT TO:.

Unique SessionHandle is passed as a DWORD.

Pointer to BSTR mailRcpt, the recipient is passed and can be modified. The call may occur multiple times for CC or BCC emails. To modify, release the string with SysFreeString and initialize a new string with SysAllocString.

Return Values

MilterAccept or MilterContinue => Recipient is accepted, and any changes are applied

MilterDenied or MilterReject => Recipient is not accepted => Email is rejected by the server

MilterTempfail => Milter error, email is accepted

function callback_header(const SessionHandle: DWORD; 
var Header: BStr): DWORD; 
    
    
    

Executed after the complete receipt of the email (SMTP command DATA .).

Unique SessionHandle is passed as a DWORD.

Pointer to BSTR Header, the complete email header is passed. To modify, release the string with SysFreeString and initialize a new string with SysAllocString.

Return Values

MilterAccept or MilterContinue => Email is accepted, and any changes are applied

MilterDenied or MilterReject => Email is not accepted => Email is rejected by the server

MilterTempfail => Milter error, email is accepted

function callback_body(const SessionHandle: DWORD; 
var Body: BStr): DWORD; 
    
    
    

Executed after the complete receipt of the email (SMTP command DATA .).

Unique SessionHandle is passed as a DWORD.

Pointer to BSTR Body, the complete email body is passed. To modify, release the string with SysFreeString and initialize a new string with SysAllocString.

Return Values

MilterAccept or MilterContinue => Email is accepted, and any changes are applied

MilterDenied or MilterReject => Email is not accepted => Email is rejected by the server

MilterTempfail => Milter error, email is accepted

function callback_abort(const SessionHandle: DWORD): DWORD;

The connection was aborted/email was not accepted by the server.

Unique SessionHandle is passed as a DWORD.

function callback_close(const SessionHandle: DWORD): DWORD;

The connection from the client to the server was interrupted.

Unique SessionHandle is passed as a DWORD.