[Mailman-Users] Mailman + Postfix

[Greg Ward]

On 18 October 2001, Alessandro Luiz Petrocino said:
> When a mail message is sent to the list address, my antivirus
> program scan the mail, searching for virus attached.
> 
> The normal process shoud be:
> - the antivirus program scan only the original message, before send this
> 
> to the list.
> 
> But, this doesn't hapen ! The antivirus program scan each mail before
> send to the user in
> the list ... with this, my server is high-loaded ...

Ouch!  I bet what's *really* happening is that incoming message are
being scanned not N times, but N+1 times: 1 when the message is received
by Postfix (before being passed to Mailman), and then once for each
recipient.  (Err, maybe not: if your Mailman is setup in the default
way, then your outgoing message will be sent 34 times -- once for each
block of 500 subscribers.  Thus, the scanner should run 35 times.  This
is still a lot worse than running once, but a lot better than running
16600 times (or whatever your N is).

> How the mailman wrapper "communicates" with the smtp server ??

Assuming you have DELIVERY_MODULE set to "SMTPDirect" (which you should,
as it's the default), Mailman will:
  * open an SMTP connection to port 25 on localhost
  * send MAIL FROM:<list-admin at your.domain>
  * send RCPT TO:<...> 500 times (for the first 500 recipients)
  * send DATA and the message body

That number 500 is configurable -- see SMTP_MAX_RCPTS in Defaults.py.

If your virus scanner is running 16,600+ times, then there's something
seriously wrong either with the scanner or your Postfix configuration.

If your virus scanner is running 35 times (1 + (16,600 / 500)), then
that is completely understandable.  I can see how you might want to
reduce it, though, as 34 of those runs are unnecessary.  However, that's
not a Mailman question -- you'll have to consult the docs for your virus
scanner.  Probably you want to skip scanning on messages with the SMTP
sender set to your list admin address.  Or something like that.

        Greg
-- 
Greg Ward - software developer                gward at mems-exchange.org
MEMS Exchange                            http://www.mems-exchange.org