Need advice on new mailserver and spam

[Scot L. Harris]

On Mon, 2005-06-06 at 11:22, Bob Brennan wrote:
> I've been called in to solve some massive email problems in a company
> that has about 30 employees and an external mailserver. They receive
> on average about 100 legitimate emails per day and 3000+ spams plus
> the usual virus and worm attacks.
> 
> I am of course recommending FC with Sendmail, Procmail, SpamAssasin
> and ClamAV on an inhouse mailserver, all of which I've had experience
> and spectacular results with.
> 
> Their spam problem, IMHO, comes from the mailserver they currently use
> accepting all non-mailbox email into a postmaster at domain.com account
> which has a quota of 1000 emails, which then sends over-quota
> rejection notices to senders for all @domain.com incoming; effectively
> shutting down all incoming email. My theory is that the reject notices
> are taken as replies by spambots and encourages even more spam.
> Short-term measures include emptying postmaster@ every 10 minutes and
> filtering for valid mis-addressed emails, but even with that the
> volume of incoming spam seriously slows down the service.
> 
> My question is - long term - is it better to set up the mailserver to
> reject all non-mailbox emails to cut down on the incoming processing
> load; or to filter and bit-bucket the spam in the hopes that the
> volume will decrease over time with no responses to the spam? Or any
> other techniques any of you are using for such problems?
> 
> Thanks in advance for opinions/suggestions,
> bob


You want to implement greylisting on that mail server asap.  It will
reduce your spam from 3000+ a day down to around 10 a day.  Seriously, I
did this for a small company and saw results like that instantly.


-- 
Scot L. Harris
webid at cfl.rr.com

"... all the modern inconveniences ..."
		-- Mark Twain