Eric Rescorla has an interesting post on his weblog at
http://www.rtfm.com/movabletype/archives/2004_07.html#001028 :
Apparently a number of people have been having problems with their
Barracuda Networks spam filters stalling. The reason as revealed today on
NANOG [1]:
On July 27th a new stream of spam was introduced into the wild. This
spam contained certain formatting aspects that were intentionally
designed to cause Spam Assassin's Bayesian implementation to run at
extremely slow speeds. Due to the way Spam Assassin handled the email,
it was taking several minutes to process these messages and the
Barracuda's internal processes would detect the potential problem and
start queuing mail to prevent any mail loss. Unfortunately this
precaution had the byproduct of further increasing the message latency
on the system.
Barracuda Networks' team of engineers created a patch for this Spam
Assassin attack. The patch was released in version 1.6.733 of the spam
definitions. If you were affected by the new spam, please make sure
you are running this version or higher of the spam definitions
(Advanced->Energize Updates in the web GUI). Also, if you had
previously contacted tech support and were advised to disable
Intention Analysis (Basic->Bayesian/Fingerprinting) as a way to
attempt to reduce latency, you should be able to turn this feature
back on without any issues.
[rest omitted]
[1]: the NANOG posting:
http://www.merit.edu/mail.archives/nanog/msg06656.html
Does anyone know what Barracuda might be talking about? Got spamples?
--j.
