Contacts error every 30 seconds: "IMAP factory connection failed"
I've just installed ML Server (2.2.1) on a Mac mini system running 10.8.4.
It's a very simple configuration, with only three services enabled: Time Machine, File Sharing, and Contacts. I have three user accounts set up. The three services appear to be working fine. A couple of laptops are using the TM service for backup. The file sharepoints are accessible to all. A number of iDevices and Macs using Contacts and/or Address Book apps are able to access a shared group of contacts on the server.
However, the Error Log for the Contacts service is reporting an error every thirty seconds:
2013-06-22 14:48:58-0400 [-] [mailgateway] 2013-06-22 14:48:58-0400 [Uninitialized] [twistedcaldav.mail.IMAP4DownloadFactory#error] IMAP factory connection failed
My troubleshooting so far indicates that this error is related to the Calendar service, which needs e-mail access in order to send out and receive event invitations. But I do not have the Calendar service enabled, nor the Mail service. (and I have no plans to turn either of these up).
Even though the Calendar service is turned off, I've checked to make sure that "Enable invitations by e-mail" checkbox is not checked. (that fix was proposed in another discussion thread here).
Can anyone explain why the server is attempting to make an IMAP connection, and more importantly, help me figure out how to stop the error messages every thirty seconds.
Thanks.