Thank you for posting your solution. I was beating my head against a wall until I came upon you post. No email invitations were being sent out to non system users. Internally, everything was working fine, but I just couldn’t get emailed invites to work. I did the things you described above, especially turning off SSL. There were some additional things that I needed to do. I had configured DNS differently than the simple DNS that the server sets up for you. By default it sets up a primary zone of server.example.com. I needed to change the zone to example.com and add an A record in that zone for the server. I also set up mail to receive mail for example.com vs. server.example.com. This was important because when you turn on “Allow invitations using email addresses” the default email address is com.apple.calendarserver@server.example.com. This didn’t work as it needed to be changed to com.apple.calendarserver@example.com.
I do have email invitations working, but there are still problems. I could not get the invitations to work with an outside mail server, with SSL on, or using a different account than the Apple provided one. Even though it’s now working, my logs are still filled with the following:
2012-02-20 11:06:17-0500 [-] [mailgateway] 2012-02-20 11:06:17-0500 [IMAP4DownloadProtocol,client] Unhandled unsolicited response: ['OK', ['HIGHESTMODSEQ', '1'], 'Highest']
2012-02-20 11:06:17-0500 [-] [mailgateway] 2012-02-20 11:06:17-0500 [IMAP4DownloadProtocol,client] Unhandled unsolicited response: ['OK', ['URLMECH', 'INTERNAL'], 'Mechanisms', 'supported']
This is true whether or not I use localhost or my servers FQDN in the mail setup for invites.
Any more thoughts on how to stop these errors?
Thanks.