I am working on an implementation of eM Client against a Stalwart IMAP/CARDDAV/CALDAV mail server implementation. When setting up an email account with all such services enabled, eM Client doesn’t respect the Autodiscover settings. As such, only IMAP is discovered and configured and a separate account for CALDAV / CARDDAV must be created. Once setup, eM Client doesn’t offer this as a location to sync Contacts, etc. This operation works without fail with Outlook and Thunderbird.
When setting up an email account with all such services enabled, eM Client doesn’t respect the Autodiscover settings.
From reading @Michal_Burger post in the following thread, the Stalwart server implementation was the issue and went against specification. eM Client was going to contact Stalwart and also try and make a workaround as per below, but I don’t know the outcome of that.