this is just an info because I did not stumble across this in the FAQ or other places, after all it is an iCal issue and not a DavDroid issue, but I hope this might be helpful for other users.
We are currently evaluating switch calendar servers from SOGo to iCal (SOGo interaction with our customer’s Exchange Servers sucks, to put it mildly). Part of the tests is checking the usage with Android phones and DavDroid (1.2.2) .
While testing on the Android phone with aCalender+ and Davdroid, I noticed, when inviting people, invites get sent out using the SOGo server but not the iCal server.
But I do see invitees on the mac client when I sync my apple calender client on the mac, so the the ical calendar knows about them, DavDrod did tell the server about them. But something in those calendar entries prevents the server from sending out invites.
The iCal calendar does send invites just fine using the Mac client app, so generally invites work on the server.
So what is the issue?
For testing I used a secondary e-mail address on the Davdroid setup. This e-mail address was not associated with the iCal server account (it was only using my primary mail address).
Once the e-mail address I used in the DavDroid setup was linked to the iCal account everything worked just fine.