[Dovecot] submission_host problem

[Marc Haber]

On Tue, Nov 15, 2011 at 09:49:20PM +0200, Timo Sirainen wrote:
> On Sat, 2011-11-12 at 05:32 +0100, Bambero wrote:
> > I configured dovecot to use submission smtp host becouse of chroot.
> > 
> > submission_host = 127.0.0.1
> > 
> > Unfortunatelly:
> > 
> > Nov 12 05:11:15 myhost exim[23366]: 2011-11-12 05:11:15 SMTP protocol
> > synchronization error (next input sent too soon: pipelining was not
> > advertised): rejected "EHLO myhost" H=localhost [127.0.0.1] next
> > input="MAIL FROM:<root at myhost>\\r\\n"
> 
> This basically says that Dovecot's SMTP client is being noncompliant,
> because Exim doesn't advertise PIPELINING extension. But I'd rather not
> add more code to fix this, since PIPELINING gives you a little bit
> better performance anyway and you can most likely fix this by modifying
> Exim's configs in some way (I can't believe Exim wouldn't support
> PIPENING..).

I have always interpreted the standard in the way that a client MUST
NOT assume that the server supports pipelining before it has
advertised PIPELINING. Since PIPELINING is only advertised after the
client has identified itself as being ESMTP compliant by saying EHLO
instead of HELO, I believe that the client MUST wait with his EHLO
until the server has shown its banner.

Forcing synchronization is a very effective means of spam protection
since most spam bots just blast away with EHLO, MAIL FROM without
bothering to wait for the server's banner.

Greetings
Marc

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