Release Notes

NixOS 26.05

• Certificate handling was simplified. We recommend setting mailserver.x509.useACMEHost to a security.acme.certs configuration. If that does not fit your requirements, configure certificate and private key using mailserver.x509.certificateFile and mailserver.x509.privateKeyFile instead. Support for automatic creation of self-signed certificates has been removed. Check the updated setup guide for a basic ACME HTTP-01 example.

• DKIM key management is now available with multiple concurrent selectors per domain enabling proper DKIM key rotation. While we still generate a default key for backwards compatibility we now also support passing pre-created key material. If your DKIM keys were automatically created before the 25.11 release they are 1024 bit RSA keys and should be rotated out. See mailserver.dkim.domains for further relevant options.

• Cleartext password files can now be configured for login accounts. This is an alternative to hashed passwords that integrates well with workflows established by agenix/sops-nix that instead rely on encryption. This option prevents files from leaking in to the Nix store. See mailserver.accounts.<name>.passwordFile.

• LDAP setups require a migration of Dovecot home directories to UUID based home directories. The exact UUID attribute can be customized through mailserver.ldap.attributes.uuid.

• The default login username for LDAP users has changed from the mail to the uid attribute. This allows users to login with their account name rather than their email address, which is more convenient and consistent with typical LDAP practices. The exact attribute can be customized through mailserver.ldap.attributes.username.

• Local and LDAP accounts can now co-exist. For overlapping names and addresses the local account will always win.

• The following integrations are deprecated and will be removed before the next release:

  • mailserver.borgbackup.enable

  • mailserver.backup.enable

  • mailserver.monitoring.enable

NixOS 25.11

• The systemName and systemDomain options have been introduced to have reusable configurations for automated reports (DMARC, TLSRPT). They come with reasonable defaults, but it is suggested to check and change them as needed.

• Support for the Sender Rewriting Scheme has been added, which allows forwarding mail without breaking SPF by rewriting the envelope address.

• The default key length for new DKIM RSA keys was increased to 2048 bits as recommended in RFC 8301 3.2. We recommend rotating existing keys, as the RFC advises that signatures from 1024 bit keys should not be considered valid any longer.

• IMAP access over port 143/tcp is now default disabled in line with RFC 8314 4.1. Use IMAP over implicit TLS on port 993/tcp instead. If you still require this feature you can re-enable it using mailserver.enableImap, but it is scheduled for removal after the 25.11 release.

• SMTP server and client now support and prefer a hybrid key exchange (X25519MLKEM768)

• SMTP access over STARTTLS on port 587/tcp is now default disabled in line with RFC 8314 3.3. If you still require this feature you can re-enable it using mailserver.enableSubmission.

• DMARC reports are now sent with the noreply-dmarc localpart from the system domain.

• DANE and MTA-STS are now validated for outgoing SMTP connections using postfix-tlspol.

• SMTP TLS connection reports (RFC 8460) are now supported using tlsrpt-reporter. They can be enabled with the mailserver.tlsrpt.enable option.

NixOS 25.05

• OpenDKIM has been removed and DKIM signing is now handled by Rspamd, which only supports relaxed canoncalizaliaton. (merge request)

• Rspamd now connects to Redis over its Unix Domain Socket by default (merge request)

  • If you need to revert TCP connections, configure mailserver.redis.address to reference the value of config.services.redis.servers.rspamd.bind.

• The integration with policyd-spf was removed and SPF handling is now fully based on Rspamd scoring. (merge request)

• Switch to the more efficient fts-flatcurve indexer for full text search (merge request).

  This makes use of a new index, which will be automatically re-generated the next time a folder is searched. The operation is now quick enough to be performed "just-in-time". Alternatively, all indices can be immediately re-generated for all users and folders by running

  doveadm fts rescan -u '*' && doveadm index -u '*' -q '*'
  

  The previous index (which is not automatically discarded to allow rollbacks) can be cleaned up by removing all the xapian-indexes directories within mailserver.indexDir.

• Individual domains can now be excluded from DMARC Reporting through mailserver.dmarcReporting.excludedDomains. (merge request)

• Configuring mailserver.forwards is now possible when the setup relies on LDAP. (merge request)

• Support for TLS 1.1 was disabled in accordance with Mozilla's recommendations. (merge request)

NixOS 24.11

• No new feature, only bug fixes and documentation improvements

NixOS 24.05

• Add new option acmeCertificateName which can be used to support wildcard certificates

NixOS 23.11

• Add basic support for LDAP users

• Add support for regex (PCRE) aliases

NixOS 23.05

• Existing ACME certificates can be reused without configuring NGINX

• Certificate scheme is no longer a number, but a meaningful string instead

NixOS 22.11

• Allow Rspamd to send DMARC reporting (merge request)

NixOS 22.05

• Make NixOS Mailserver options discoverable from search.nixos.org

• Add a roundcube setup guide in the documentation

NixOS 21.11

• Switch default DKIM body policy from simple to relaxed (merge request)

• Ensure locally-delivered mails have the X-Original-To header (merge request)

• NixOS Mailserver options are detailed in the documentation

• New options dkimBodyCanonicalization and dkimHeaderCanonicalization

• New option certificateDomains to generate certificate for additional domains (such as imap.example.com)

NixOS 21.05

• New fullTextSearch option to search in messages (based on Xapian) (Merge Request)

• Flake support (Merge Request)

• New openFirewall option defaulting to true

• We moved from Freenode to Libera Chat

NixOS 20.09

• IMAP and Submission with TLS wrapped-mode are now enabled by default on ports 993 and 465 respectively

• OpenDKIM is now sandboxed with Systemd

• New forwards option to forwards emails to external addresses (Merge Request)

• New sendingFqdn option to specify the fqdn of the machine sending email (Merge Request)

• Move the Gitlab wiki to ReadTheDocs