Icedove asks at start for the calendar password, but does not accept
it (i.e. asks
again and again until I click "Cancel").
The calendar does not work than - probably because of the missing password.
The server works with a valid GeoTrust certificate, that will not expire soon.
Currently, I have this problem with a local Jessie backport of
calendar-exchange-provider
(3.4.0-1~bpo8+0.1). It does, however, relate to the version of
icedove. When I downgrade
to 31.7.0-1~deb8u1, the calendar works.
Therefore I assigned the bug to Icedove, not to
calendar-exchange-provider, but maybe
maintainers see this differently?