Glad I found this. For reference, I set up the following records for a standard Cloudron install with active E-Mail handling and Nextcloud dealing with Card- and CalDAV.
TXT _caldavs._tcp.cloud.$DOMAIN "path=/remote.php/dav" TXT _carddavs._tcp.cloud.$DOMAIN "path=/remote.php/dav" SRV _sieve._tcp.$DOMAIN my.$DOMAIN - PORT 4190 SRV _autodiscover._tcp.$DOMAIN my.$DOMAIN - PORT 443 CNAME autodiscover.$DOMAIN - my.$DOMAIN. SRV _carddavs._tcp.$DOMAIN cloud.$DOMAIN - PORT 443 SRV _carddav._tcp.$DOMAIN cloud.$DOMAIN - PORT 80 SRV _caldav._tcp.$DOMAIN cloud.$DOMAIN - PORT 80 SRV _caldavs._tcp.$DOMAIN cloud.$DOMAIN - PORT 443 SRV _submission._tcp.$DOMAIN my.$DOMAIN - PORT 587 SRV _imaps._tcp.$DOMAIN my.$DOMAIN - PORT 993
- _submission._tcp, _imaps._tcp, _autodiscover._tcp (as well as autodiscover CNAME) and _sieve._tcp are valid for any installation where E-Mail for a domain is handled by Cloudron. These records help clients (Thunderbird, Smartphone Mail Apps, etc) to automatically discover the correct IMAP/SMTP Hostnames + Ports. In most cases, with these records set you can have Thunderbird automatically configure your Mailaccount by simply giving the mail address (e.g. email@example.com)
- _carddav*/_caldav* SRV Records should be set by the respective Apps dealing with the protocols (Sogo, Nextcloud, etc) as the redirection should be pointed to the App's subdomain
- _caldavs/_carddavs* TXT Records should also be set by the respective Apps, as they instruct DAV clients where to find the concrete path DAV-Requests are handled (does the same as .well_known on the webserver; according to some docs and posts in the internet, these records (SRV+TXT) are required for MacOS/iOS clients to correctly discover and connect)
There are certainly more things that can be done with this. In general, this is a massive UX plus. DavDroid and Thunderbird both are able to automatically connect and discover everything needed by simply providing the $USER@$DOMAIN E-Mail adress during account setup. Will test more clients today, but I'm sure many follow these standards.