North American Network Operators Group|
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Re: Barracuda Networks Spam Firewall
Sadly, they have not responded to my email on the topic, sent four days ago.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 cause.
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.