mailcow-dockerized-docs/docs/u_e-autodiscover_config.md

Open/create data/web/inc/vars.local.inc.php and add your changes to the configuration array.

Changes will be merged with "$autodiscover_config" in data/web/inc/vars.inc.php):

<?php
$autodiscover_config = array(
  // General autodiscover service type: "activesync" or "imap"
  // emClient uses autodiscover, but does not support ActiveSync. mailcow excludes emClient from ActiveSync.
  'autodiscoverType' => 'activesync',
  // If autodiscoverType => activesync, also use ActiveSync (EAS) for Outlook desktop clients (>= Outlook 2013 on Windows)
  // Outlook for Mac does not support ActiveSync
  'useEASforOutlook' => 'yes',
  // Please don't use STARTTLS-enabled service ports in the "port" variable.
  // The autodiscover service will always point to SMTPS and IMAPS (TLS-wrapped services).
  // The autoconfig service will additionally announce the STARTTLS-enabled ports, specified in the "tlsport" variable.
  'imap' => array(
    'server' => $mailcow_hostname,
    'port' => array_pop(explode(':', getenv('IMAPS_PORT'))),
    'tlsport' => array_pop(explode(':', getenv('IMAP_PORT'))),
  ),
  'pop3' => array(
    'server' => $mailcow_hostname,
    'port' => array_pop(explode(':', getenv('POPS_PORT'))),
    'tlsport' => array_pop(explode(':', getenv('POP_PORT'))),
  ),
  'smtp' => array(
    'server' => $mailcow_hostname,
    'port' => array_pop(explode(':', getenv('SMTPS_PORT'))),
    'tlsport' => array_pop(explode(':', getenv('SUBMISSION_PORT'))),
  ),
  'activesync' => array(
    'url' => 'https://'.$mailcow_hostname.($https_port == 443 ? '' : ':'.$https_port).'/Microsoft-Server-ActiveSync',
  ),
  'caldav' => array(
    'server' => $mailcow_hostname,
    'port' => $https_port,
  ),
  'carddav' => array(
    'server' => $mailcow_hostname,
    'port' => $https_port,
  ),
);

To always use IMAP and SMTP instead of EAS, set 'autodiscoverType' => 'imap'.

Disable ActiveSync for Outlook desktop clients by setting "useEASforOutlook" to "no".