This incident has been resolved.

The spam emails are coming from Google's mail system. We have blocked all connections from Google's mail system while we investigate. We realize this is a problem as legitimate mail from Google will be blocked while we figure this out. We have opened an abuse report with Google.

We are receiving a tremendous amount of spam addressed to users on our email platform. The large volume of spam is overwhelming our spam filtering systems and creating overall slow response times in all mail systems. We are working at cutting off the spam from its upstream source.

All mail systems are experiencing degraded service. This includes outbound (SMTP), inbound (POP3, IMAP), and email marketing.