Rate question

[Jeff <pr...@mrbonkers.org>]

I've seen an installation where postfix handed off mail directly to 
spamd, treating it as a policy server in smtpd_recipient_restrictions.  
I was thinking about doing this for a server with several thousand users 
and heavy usage. In that configuration, how would spamd behave under 
load? Is it likely to cause problems? Should I be using amavis? What's 
the best way to get mail to spamd when the volume is high?

RE: Rate question

[Giampaolo Tomassoni <g....@libero.it>]

Please note I'm not using that way, nor I'm using spamd.

That said.


From: Jeff [mailto:precinct@mrbonkers.org]
> 
> I've seen an installation where postfix handed off mail directly to 
> spamd, treating it as a policy server in smtpd_recipient_restrictions.
> I was thinking about doing this for a server with several thousand users 
> and heavy usage.

> In that configuration, how would spamd behave under load?

It would work more or less how it works in the more classical content filtering case, so I guess it wouldn't matter how you invoke it.


> Is it likely to cause problems?

I *guess* that the way you describe wouldn't allow the destinating user to have control of received spam. I mean, he/she wouldn't have a 'spam' folder in its mailbox. This may be a problem in case of false positives.

BUT, also note that this way the senders gets informed of the undelivered message, since the postfix's connecting peer would get a 5xx error and, in case of a legitimate sender, he/she would easily get a bounce mail back from his/her smtp server.

The 5xx error is not that bad in this, but also exposes a neck to spammers: since they have a feedback from your antispam engine, they may attempt multiple versions of their "payload" 'till they get into...


> Should I be using amavis?

I use it and I'm fine with it, but I don't see an easy way to integrate smtpd_recipient_restrictions with amavisd-new: amavis is designed to resubmit legitimate messages for final delivery to the MTA, so I don't see how could this cope with refusing the message at whole.

However, if you forget the smtpd_recipient_restrictions way, you would get even antivirus handling thanks to amavis.


> What's the best way to get mail to spamd when the volume is high?

Actually, greylisting: you may decrease the inboung e-mail traffic a lot.

giampaolo