Set Up Dovecot IMAP Server with Postfix on Linux

Dovecot is the IMAP server that lets mail apps and webmail read mailboxes. Paired with Postfix it forms a complete self-hosted mail server: Postfix receives and sends, Dovecot stores and serves. This guide sets up Dovecot with system users, TLS and Postfix integration.

Before you start

A Linux VPS with Postfix already accepting mail for your domain (MX record pointing to the server, mydestination including your domain).
A TLS certificate for the mail hostname, for example from Let's Encrypt for mail.example.com.
Ports 25, 587 and 993 open.

Tip: Self-hosted email takes ongoing care. On MdmHost cPanel hosting, Dovecot and Exim are already configured and maintained for you.

Install Dovecot

Ubuntu/Debian: sudo apt install -y dovecot-imapd dovecot-lmtpd
AlmaLinux/Rocky: sudo dnf install -y dovecot && sudo systemctl enable dovecot

Settings are split across /etc/dovecot/conf.d/.

Configure mail storage

In 10-mail.conf:

mail_location = maildir:~/Maildir

Each user's mail is stored as files in ~/Maildir.

Require TLS and secure authentication

In 10-ssl.conf:

ssl = required
ssl_cert = </etc/letsencrypt/live/mail.example.com/fullchain.pem
ssl_key = </etc/letsencrypt/live/mail.example.com/privkey.pem
ssl_min_protocol = TLSv1.2

In 10-auth.conf:

disable_plaintext_auth = yes
auth_mechanisms = plain login

In 10-master.conf, disable plain IMAP on 143 by setting its port = 0 inside inet_listener imap, and keep imaps on 993.

Deliver mail from Postfix via LMTP

In 10-master.conf, expose LMTP to Postfix:

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

In Postfix's main.cf:

mailbox_transport = lmtp:unix:private/dovecot-lmtp

Let Postfix authenticate users through Dovecot

In Dovecot's 10-master.conf:

service auth {
  unix_listener /var/spool/postfix/private/auth {
    mode = 0660
    user = postfix
    group = postfix
  }
}

In Postfix's master.cf, enable the submission service on port 587 with:

submission inet n - y - - smtpd
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_sasl_type=dovecot
  -o smtpd_sasl_path=private/auth
  -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject

Restart both: sudo systemctl restart dovecot postfix.

Test the server

Check the config: doveconf -n.
Test TLS on IMAP: openssl s_client -connect mail.example.com:993 – you should see the Dovecot greeting.
Add the account in a mail app: IMAP mail.example.com port 993 SSL/TLS; SMTP port 587 STARTTLS; username is the Linux user.
Send a message to the account and watch journalctl -u dovecot -f for a successful LMTP delivery.

Troubleshooting

Login fails: check journalctl -u dovecot; make sure the user exists and has a password.
Postfix "connect to private/dovecot-lmtp: No such file": the socket path or permissions in 10-master.conf do not match.
Certificate warnings in mail apps: the certificate does not cover the hostname clients use.
Mail delivered to /var/mail instead of Maildir: mailbox_transport is not set in Postfix.

FAQ: Dovecot IMAP server

Can I use virtual users instead of Linux accounts?

Yes. Dovecot supports password files and SQL databases for virtual mailboxes; it is more setup but scales better.

Should I enable POP3?

Only if users need it. IMAP keeps mail in sync across devices, which suits most people.

How do I add spam filtering?

Add Rspamd or SpamAssassin as a Postfix milter, and use Dovecot's Sieve plugin to file spam into a Junk folder.

Next steps

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