We migrated from an old Horde to SOGo in our company a couple of days ago, and one of the annoying issues we experience is that email invitations to attendees apparently do not work properly, which might be a show stopper for us:

• We have a functional non-person account ("office") that holds relevant company-wide calendars. ("meetings", for instance)

• Team members that are supposed to create events have all the permissions on those calendars, that is - change permission for all 3 privacy levels as well as add and delete permissions.

• Team members have subscribed to those calendars.

• Team members have imported those calendars into Thunderbird/Lightning using CalDAV and are able to view and edit all events.

• Now when creating an event in Thunderbird on that "meetings" calendar and adding attendees, no email invitations are sent, which is a big problem for us.

Some observations I made while trying to find something out about the issue:

• When creating the event with attendees in the web interface, invitations will be sent (however, on behalf of the "office" user instead of the person creating the event, which is another unfortunate annoyance, but a different issue 0002702).
• When creating an event in a Personal Calender in Thunderbird, invitations are also successfully sent.
• There is no obvious difference in the new event window between creating an event in a Personal Calender and a subscribed calendar (with full permissions). The "notify attendees" is checked in both cases and grayed out in both cases.
• I can see no error messages in the sogo.log.

What do we need to do in order to have invitations sent in all cases?

Do you want us to do any steps to further debug the issue?