Today, as part of our effort to move people away from Outlook and onto Thunderbird, I thought I’d have another look into autoconfiguring it. We already have it working for email setups, but Thunderbird now supports Calendars and Contacts as well using CalDAV and CardDAV protocols.
After some googling and much assistance from claude.ai, we finally found a solution, so here goes…
First of all, for my example, I’m going to use this domain. We have this setting in the DNS:
autoconfig.adrianmardlin.me IN CNAME mail.verygoodemail.com.
Our IMAP/POP3/SMTP is all available via mail.verygoodemail.com, whereas Calendars and Contacts are both at https://cal.verygoodemail.com
The autoconfig causes it to load a file called config-v1.1.xml. You can see the contents at https://www.verygoodemail.com/mail/config-v1.1.xml
As you can see in there, I added two sections in there for Calendars and Contacts. This did not work. Claude.ai seems to think that it may work in the future so I’m leaving it there.
So, it turns out the only way to make it work at the moment is through RFC6764. The way this seems to work is it will first look for some DNS records, and if that fails it will look for https://adrianmardlin.me/.well-known/caldav and /carddav.
As we don’t normally control the websites for our customers, we have to take the DNS route, so the following needs to be added:
_caldavs._tcp.adrianmardlin.me. IN SRV 0 0 443 cal.verygoodemail.com.
_caldavs._tcp.adrianmardlin.me. IN TXT "path=/"
_carddavs._tcp.adrianmardlin.me. IN SRV 0 0 443 cal.verygoodemail.com.
_carddavs._tcp.adrianmardlin.me. IN TXT "path=/"
And bingo, it works. This now means that for all our customer DNS records, in order for them to be able to autoconfigure with Thunderbird, we add the following records:
autoconfig CNAME mail.verygoodemail.com.
_caldavs._tcp IN SRV 0 0 443 cal.verygoodemail.com.
_caldavs._tcp IN TXT "path=/"
_carddavs._tcp IN SRV 0 0 443 cal.verygoodemail.com.
_carddavs._tcp IN TXT "path=/"
And make sure that https://autoconfig.customerdomain/mail/config-v1.1.xml resolves and works.
That was 4 hours of my life that I’ll never get back. Hopefully you’ll find this and waste less of yours.