We were getting a lot of spam messages, roughly 70,000 per day, sent to our customers which we then forwarded as requested. People received the spam and marked it such, but it was our server that took the hit, not the original sender. This resulted in us being blacklisted as a spam source, not to mention the slow delivery caused by the clogged server.
We have been working hard to repair these issues over the last couple of weeks and all is working well now. If something like this does happen again, we will be sure to send out a mailer or other notification. Our apologies for not doing so this time.