Earlier today we encountered several tempfail mail delay scenarios due to a piece of software relying on DSBL realtime blacklist that was no longer actively maintained. We have taken action to remove DSBL from our web hosting mail servers which has resolved any delays and is currently processing the mail backlog.
Note: The issue only applied to mail1.ownwebnow.com. It did not affect any other services, such as Exchange hosting or ExchangeDefender. The issue was resolved and there should be no delays on the network at this time.