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:

.. csv-table:: Resource record set
   :header: "Name", "TTL", "Type", "Priority", "Weight", "Port", "Value"
   :widths: 30, 5, 5, 5, 5, 5, 20

   _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
:option:`mailserver.enableSubmission` and :option:`mailserver.enableImap`,
because they only support connections with explicit TLS. These services are
disabled by default because they are deprecated through `RFC8314 4.1`_.

.. csv-table:: Resource record set
   :header: "Name", "TTL", "Type", "Priority", "Weight", "Port", "Value"
   :widths: 30, 5, 5, 5, 5, 5, 20

   _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.

.. _mobileconfig: https://support.apple.com/de-de/guide/profile-manager/pmdbd71ebc9/mac
.. _Autodiscover: https://learn.microsoft.com/en-us/exchange/architecture/client-access/autodiscover?view=exchserver-2019
.. _Autoconfig: https://benbucksch.github.io/autoconfig-spec/draft-ietf-mailmaint-autoconfig.html
.. _automx2: https://github.com/rseichter/automx2
.. _RFC6186: https://www.rfc-editor.org/rfc/rfc6186
.. _RFC8314 4.1: https://www.rfc-editor.org/rfc/rfc8314#section-4.1