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Re: timeoutsmtpd downsides

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Subject: Re: timeoutsmtpd downsides
From: Sami Farin <safari-qmail@safari.iki.fi>
Date: Wed, 4 Apr 2007 23:08:30 +0300
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On Wed, Apr 04, 2007 at 12:50:32 -0600, Kyle Wheeler wrote:
> Hello,
> 
> Because of some recent spammer behavior (looks like 
> reverse-tarpitting), I'm considering reducing my timoutsmtpd value 

Are you using bannerdelay feature?

> from the default 1200 seconds to 60 or less. I haven't really 
> thoroughly considered the repercussions of such an action, but it 
> seems to me that there's very little reason to wait more than a few 
> seconds for each new piece of data from the client. I don't see any 
> requirement in the SMTP protocol that I must wait for a particularly 
> long amount of time...
> 
> Are there drawbacks to lowering my timeout value that I'm not thinking 
> of? Has anyone done this before and have any reports as to possible 

Some SMTP clients (e.g. postfix, zmailer, ...) keep the connection open
in case some new email for the domain needs to be delivered
(mailing lists are a good example).
If you make the timeout very small, they just have to make more
connections.  Not necessarily very worrisome, but what
if they think your SMTP server keeps dying for no reason
and slow down deliveries or something?  If this seems to happen,
you can always add TIMEOUTSMTPD env var feature =)

> side-effects?
> 
> ~Kyle

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