Dovecot on Ubuntu 24.04 LTS by cloudimg

Dovecot is one of the most widely deployed open source IMAP and POP3 servers in the world, chosen for its security focus, standards compliance and excellent performance. This cloudimg image delivers Dovecot fully installed and configured on Ubuntu 24.04 LTS as a self contained, secure by default single node mail store, so a secure mailbox server is running within minutes of launch.

One virtual mailbox is provisioned with its mail kept in Maildir format under a dedicated unprivileged account, mail is delivered locally over LMTP, and IMAP and POP3 are served over TLS: IMAP on 993 (implicit TLS) and 143 (STARTTLS), and POP3 on 995 (implicit TLS) and 110 (STARTTLS). Any standards compliant mail client can connect securely.

Security is built in, with no default credential. On the first boot of every VM a one shot service generates a unique mailbox password, hashes it into the Dovecot password database, regenerates the TLS private key and certificate, and writes the plaintext login to a root only file. Plaintext authentication is refused on the non TLS ports until the connection is upgraded with STARTTLS, and only the virtual mailbox user can authenticate. The captured image ships no certificate, no password and an empty password database, so no mailbox can authenticate until first boot provisions the instance.

Read the per instance mailbox login from the root only credentials file, point any IMAP or POP3 client at the VM over TLS, add further mailboxes, and front Dovecot with an MTA such as Postfix for a complete mail stack, per the guide. Dovecot is dual licensed MIT and LGPL 2.1, free and open source. cloudimg is not affiliated with or endorsed by the Dovecot project or Open-Xchange. cloudimg provides packaging, hardening, security patching, and 24/7 support.