#380 CalDav protocol error

[David Potterveld]

I believe there is a protocol error in the CalDav server code. This has cropped up when using Thunderbird 78.0 with its new, internal support for CalDav calendars. (Everything was working fine with TB68+Lightning.) Bug reports have been filed with Mozilla, for more technical details see for example:

https://bugzilla.mozilla.org/show_bug.cgi?id=1649036

The issue is caused by DavMail not providing D:supported-report-set' in the response to the first PROPFIND sent by TB. From my quick read of RFC4791, it looks to me like it is REQUIRED to provide 'supported-report-set' and TB78 is technically correct in aborting processing, which results in the calendar failing to sync.

Although the TB maintainers appear to be crafting a patch to ignore this deficiency, as apparently the old Lightning was doing, it would probably be good for DavMail to fix this problem too by providing the required response. Could this be looked at?

Thanks!
-David