[Fri Nov 16 07:52:11.610680 2018] [:error] [pid 4018] [client 18.104.22.168:56164] Exception in /usr/share/groupoffice/modules/calendar/controller/EventController.php at line 200: Ask permission, referer: https://a.b.c/groupoffice/
[Fri Nov 16 07:52:15.421428 2018] [:error] [pid 4018] [client 22.214.171.124:56164] ErrorException in /usr/share/groupoffice/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php at line 94: stream_socket_enable_crypto(): Peer certificate CN=`a.b.c' did not match expected CN=`localhost', referer: https://a.b.c/groupoffice
I have installed Group Office mailserver (6.3.50) on a Debian 9.5 server. The server use tls encryption and certificates for apache, postfix, dovecot and groupoffice. Https connections and sending/receiving emails via Groupoffice works fine except for calendar notifications. The error messages above are from the apache2/error.log file. They appear when a calendar event has been created and e-mails to participants are about to be sent.
To me it looks as if the swiftmailer used by the calendar module just tries to send via "localhost" without checking the smtp/imap settings in Groupoffice.
Any ideas about a solution is most welcome.