We're having email delays to some recipients when sending from Outlook via our Exchange 2010 server. Our email system uses an external spam filter run by Microsoft at filter.itsafemail.com. Here is the error message we are receiving:
Delivery is delayed to these recipients or groups:
Subject: ABC Contribution 2/16-2/22
This message hasn't been delivered yet. Delivery will continue to be attempted.
The server will keep trying to deliver this message for the next 1 days, 19 hours and 51 minutes. You'll be notified if the message can't be delivered by that time.