Autodiscovery

RFC6186 defines how email clients can automatically discover a mail server's SMTP and IMAP endpoints. To enable this, the following DNS records must be configured:

Resource record set

Name	TTL	Type	Priority	Weight	Port	Value
_submissions._tcp.example.com.	3600	SRV	10	1	465	mail.example.com.
_imaps._tcp.example.com.	3600	SRV	10	1	993	mail.example.com.

Legacy records

The following DNS records are only supported with mailserver.enableSubmission and mailserver.enableImap, because they only support connections with explicit TLS. These services are disabled by default because they are deprecated through RFC8314 4.1.

Resource record set

Name	TTL	Type	Priority	Weight	Port	Value
_submission._tcp.example.com.	3600	SRV	20	1	587	mail.example.com.
_imap._tcp.example.com.	3600	SRV	20	1	143	mail.example.com.

Client support

As researched in March 2026

Only a small number of MUAs currently implement this. The most common concern from the bigger and security-conscious vendors is lack of widespread DNSSEC propagation that could be used to authenticate these SRV records.

• Aerc: since 0.20.1

  • _submissions._tcp support submitted in https://lists.sr.ht/~rjarry/aerc-devel/patches/68173

• Evolution: Since 3.49.3 for mail accounts

  • https://gitlab.gnome.org/GNOME/evolution/-/wikis/Autoconfig

  • https://gitlab.gnome.org/GNOME/evolution/-/issues/941

Unsupported

• DeltaChat:

  • https://github.com/chatmail/core/issues/1508

• Thunderbird:

  • Desktop: https://bugzilla.mozilla.org/show_bug.cgi?id=342242

  • Android: https://github.com/thunderbird/thunderbird-android/issues/4721

Vendor-specific autoconfig

The automx2 service can provide autoconfig support for Apple's mobileconfig, Microsoft's Autodiscover and Mozilla's Autoconfig standards. It does however lack support for multiple mail domains and isn't open for contributions due to copyright concerns.