I have an OCS 2007 Enterprise deployment with consolidated edge server. Everything works great federation works PIC works but we only have MSN and from the communicator side all messages get sent fine, from the MSN side about every third message gets an error that the message can't be sent but do it again and its fine. I am also getting this error on my edge server but I don't know if it is related.
Category 1001 and Event ID 14502 : Server fed.messenger.msn.com IP address x.x.x.x there has been 139 errors in the last 180 min. Failure type 80072746 occurred 12199 times and 80072745 occurred 26 times.