Barracuda Networks Spam Firewall

Jared B. Reimer jared at
Mon May 17 21:26:37 UTC 2004

>Did you not receive some basic support from them during your
>evaluation? A perceived 90% drop in performance is pretty significant
>and I'd imagine that they'd be interested in helping to determine the

Sadly, they have not responded to my email on the topic, sent four days ago.

However, someone unrelated to the company emailed me off-list saying that 
basically this is a known flaw in the product with back-end systems like 
qmail that asynchronously bounce mail for invalid recipients.  See below quote:

>We had this problem when our inbound-smtp server ( the server the 
>barracuda is dumping mail to) was accepting all RCPT TOs:   As a result 
>dictionary attacks were getting through and creating 'unique recipients' 
>on the Barracuda.   As soon as I fixed my mail server to reject with a 220 
>error on bogus RCPT TOs  the problem cleared up.

This is a pretty serious flaw IMHO, if it is (in fact) true.  qmail isn't 
the only mailer that behaves this way.  It looks like they may have tried 
to kludge their way around this with LDAP in the case of MS Exchange, which 
also does asynchronous bouncing of undeliverable mail IIRC.

-- Jared

More information about the NANOG mailing list