Understanding dovecot_virtual_delivery in Dovecot

Table of Contents: What is dovecot_virtual_delivery? Check Dovecot Mail Delivery Method Verify Dovecot Virtual Mailbox Configuration Check LMTP Configuration Fix Mail Directory Permissions Check Mail Logs for Errors Summary

What is dovecot_virtual_delivery?

If you are facing mail delivery issues related to Dovecot's virtual user system, the problem may be with:

• Dovecot LDA (Local Delivery Agent) – Handles local mail delivery to mailboxes
• Dovecot LMTP (Local Mail Transfer Protocol) – Modern protocol for efficient virtual mail delivery
• Virtual Mailbox Configuration – Incorrect paths or database settings
• Incorrect Permissions on Mail Directories – Dovecot can't write to mail storage

Check Dovecot Mail Delivery Method

Dovecot delivers emails in two common ways:

1. LDA (Local Delivery Agent) > Used when Dovecot handles local mail delivery directly.
2. LMTP (Local Mail Transfer Protocol) > Used for virtual mail users and integrates better with Postfix; more efficient for high-volume mail servers.

Check which method your system uses:

If using LDA, you might see:

mail_plugins = sieve
protocol lda {
    mail_plugins = $mail_plugins sieve
}

If using LMTP, you might see:

protocol lmtp {
    mail_plugins = quota sieve
}

Verify Dovecot Virtual Mailbox Configuration

If your system uses virtual mail users, make sure Dovecot is properly configured.

Check Dovecot Virtual Mail Setup

Edit the main Dovecot configuration file:

Ensure the following settings are correct for a typical Maildir setup:

mail_location = maildir:/var/mail/vhosts/%d/%n

Where:

• %d > Domain name (e.g., example.com)
• %n > Username (e.g., john)

If using a MySQL/PostgreSQL backend for user authentication, also check these typically associated settings:

mail_home = /var/mail/vhosts/%d/%n
mail_location = maildir:/var/mail/vhosts/%d/%n/Maildir

Apply changes and restart Dovecot:

Check LMTP Configuration

If using Dovecot LMTP (recommended), ensure it's properly configured to communicate with Postfix.

Edit the master configuration file:

Look for a section similar to this (location may vary by distribution):

service lmtp {
    unix_listener /var/spool/postfix/private/dovecot-lmtp {
        mode = 0600
        user = postfix
        group = postfix
    }
}

In Postfix (/etc/postfix/main.cf), ensure mail delivery is delegated to Dovecot's LMTP socket:

mailbox_transport = lmtp:unix:private/dovecot-lmtp
# or for virtual_transport if using virtual domains:
virtual_transport = lmtp:unix:private/dovecot-lmtp

Restart both services:

Fix Mail Directory Permissions

The most common virtual delivery failure is incorrect permissions. Dovecot needs to write to the mail storage directory.

1. Ensure the dedicated vmail user exists:

If the user doesn't exist, create it:

2. Set correct ownership on your mail storage directory:

3. In Dovecot configuration (/etc/dovecot/conf.d/10-mail.conf), set the user and group:

mail_uid = vmail
mail_gid = vmail

4. Restart Dovecot:

Check Mail Logs for Errors

If mail delivery still fails, check system logs for specific error messages.

Check Dovecot service logs:

Check general mail logs:

Common errors and their meanings:

• "Mailbox not found" > Incorrect mail_location path or missing directory.
• "Permission denied" > Wrong ownership or permissions on mail directory.
• "Connection refused" > LMTP service not running or wrong socket path.
• "User doesn't exist" > Authentication/user database misconfiguration.

Summary

By systematically checking these configuration areas, your Dovecot virtual mail delivery should work correctly!