May 29, 2012 8:30am — It looks like our email server has been blacklisted by SORBS and Spamcop. We had a user whose computer was compromised and was sending out thousands of Viagra emails. We have blocked the account and are working on getting the server delisted from the spam blacklists. In the mean time, our customers may see some of their email returned because of the blacklisting.
Update 9:15am — Our server has been removed from the Spamcop list, which is the one used by most ISPs. We are still working on SORBS, but very few providers utilize that list because of the large number of false positives, so we do not expect any issues for our customers from this point.