Over the weekend, one of our hosted e-mail users had a weak password, and spammers worldwide were trying to use our e-mail server to send out e-mail. Our built in spam checks helped mitigate the attack, but by this morning, our reputation had slipped into a Poor category as determined by Cisco’s SenderBase – http://www.senderbase.org/senderbase_queries/detailip?search_string=18.104.22.168
Some users may experience delivery delays or bounces based on the drop in reputation. Please re-send items that have bounced at this point. We have isolated the incident, and taken actions to help catch these types of events moving forward. In the meantime, we have re-routed our e-mail out a different mail server with a Neutral reputation, which will upgrade to Good by the end of today. Once the current mail server reputation drops, we will undo this temporary reroute.
Let us know if you have any questions, and thanks for your patience.