Our filtering system (Barracuda) appears to have had an update applied that is causing it to falsely flag some emails (typically with attachments) as SPAM or even a virus. We are fairly certain that these flags are incorrectly being applied after this update and we are working with the vendor to correct the issue. Unfortunately there isn't a whole lot we can do to allow these messages until the vendor provides a resolution.
Please note that the messages that seem to be getting stopped are very minimal, and it is inconsistent. (It looks like approximately 10-12 messages out of the last few thousand messages were stopped/flagged incorrectly.) This should not impact most users for their normal daily use of email, but please be aware of the issue in case you send an email with an attachment and the recipient says that it was not received.