Staff are investigating the problem and will post updates here as we learn more.
[2016-06-16 23:13:57 | Rob McNicholas]
The delays in mail delivery since the Sympa 6.2 upgrade seem to have been due to a combination of changes in the architecture of the new version of Sympa and our spam load. Spam messages sent to Sympa’s mail interface are generating internal loops and huge loads which subsequently delay legitimate mail.
Additional scanning and immediate rejection of messages containing viruses and mail from [known spamming sites](http://dnsrbl.org) has improved performance dramatically. This has been accomplished using a combination of [MIMEDefang, Spamassassin, and ClamAV](http://www.mickeyhill.com/mimedefang-howto/) to implement a sendmail milter which scans and optionally rejects incoming messages at the time of delivery.
At this time we believe the server is no longer delaying legitimate mail, but it will need to be closely monitored for a few days until we are confident the problem has been resolved. Any future updates will be posted to this article.
If you are noticing any problems with non-delivery of mail which you believe is due to this additional scanning, please mail us at email@example.com and we will investigate.
Resolved as of 2016-06-20 21:52:00