Status (by brong at Tue Sep 20 18:51 UTC)
New users may experience some delays to outgoing mail while we are taking care of misuse of our systems by spammers. Signup for new guest accounts is also temporarily disabled.
Update (by brong at Tue Sep 20 21:38 UTC)
All the accounts that were part of this spamming run have now been blocked, and the half a million!!! emails still in the outbound queue have all been detected and purged. Everything is back to normal.
Update (by brong at Tue Sep 20 21:38 UTC)
… except that we’re leaving guest signups blocked until we can come up with a better way to stop this happening again. At least until it’s daytime for someone who is working on it.