are you using postscreen by any chance?

it's seems like the network layer between the client and the server is fine.

can you see anything on the maillog when the session was started?
is this happening on every session or just part of them?

as i remember a 4XX errors aborted transmissions will be retransmitted.

Eliezer

On 03/05/2012 01:05, Nikolaos Milas wrote:
Hi,

Tonight we are getting frequent (at times, otherwise occasional) errors
coming in to the postmaster, like the following (see below).

Note: the session is from our mail gateway machine to the final
(internal) destination one (Postfix).

I would say that these errors (which we have not seen before) are caused
by observed network (or other) instability on the VM infrastructure
which is not controlled by us (Postfix 2.8.3/Centos 5 is on it as a KVM
guest).

Questions:

1. Does my guess for the cause of the problem really seems valid
(network instability/timeouts which occur)?
2. I can't find any related events logged in the maillog. Should I, or
is it expected that sessions like that are not logged?
3. Such events which indicate a failed mail transmission attempt
("session aborted"), imply that the original client will retry or not?

Just in case, I've restarted Postfix and I'll see how it goes.

Any comments/suggestions to improve the situation (assuming that the
problem is transient)?

Thanks,
Nick

-------- Original Message --------

Subject: Postfix SMTP server: errors from
mailgw.admin.noa.gr[195.251.204.12]
Date: Wed, 2 May 2012 23:25:03 +0300 (EEST)
From: mailer-dae...@vmail.noa.gr (Mail Delivery System)
To: postmas...@noa.gr (Postmaster)


Transcript of session follows.

Out: 220 vmail.noa.gr ESMTP Postfix
In: EHLO mailgw.admin.noa.gr
Out: 250-vmail.noa.gr
Out: 250-PIPELINING
Out: 250-SIZE 41943040
Out: 250-VRFY
Out: 250-ETRN
Out: 250-STARTTLS
Out: 250-ENHANCEDSTATUSCODES
Out: 250-8BITMIME
Out: 250 DSN
In: MAIL FROM:<nspiresdep-h...@nasaprs.com> SIZE=3194
Out: 250 2.1.0 Ok
In: RCPT TO:<us...@noa.gr>
Out: 250 2.1.5 Ok
In: DATA
Out: 354 End data with <CR><LF>.<CR><LF>
Out: 451 4.3.0 Error: queue file write error

Session aborted, reason: lost connection

For other details, see the local mail logfile

-------------------------------------------------------


--
Eliezer Croitoru
https://www1.ngtech.co.il
IT consulting for Nonprofit organizations
eliezer <at> ngtech.co.il

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