From: Wietse Venema (wietseporcupine.org)
Date: Fri Apr 13 2007 - 07:04:27 CDT

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Rob Sterenborg:
> Out: 220 mx3.netsourcing.nl ESMTP Postfix
> In: EHLO mail.pleyade.nl
> Out: 250-oehoe.dcyb.net
> Out: 250-PIPELINING
> Out: 250-SIZE 15360000
> Out: 250-VRFY
> Out: 250-ETRN
> Out: 250-ENHANCEDSTATUSCODES
> Out: 250-8BITMIME
> Out: 250 DSN
> In: MAIL FROM:<xxxxpleyade.nl>
> Out: 250 2.1.0 Ok
> In: xxxxrelay-domain.nl
> Out: 502 5.5.2 Error: command not recognized
>
> Session aborted, reason: lost connection
> =================
>
> Clearly, what went wrong is that the MTA failed to send "RCPT TO: " in
> front of the recipient email address. (I sniffed the line and it's
> actually sent like this so it's not a problem on our side.) It doesn't
> always happen: most email from these domains (97-99% or so) is delivered
> normally.
>
> So far, the only thing these MTA's seem to have in common is that they
> are Novell GroupWise servers:

If your sniffer confirms that no "RCPT TO:" is sent, then perhaps
the cause is a buggy PIPELINING implementation on the sending side.

If you have Postfix 2,3 or later, you can selectively turn off
the PIPELINING announcement with:

/etc/postfix/main.cf:
    smtpd_discard_ehlo_keywords = pipelining

Or, more selectively:

/etc/postfix/main.cf:
    smtpd_discard_ehlo_keyword_address_maps = hash:/etc/postfix/broken_clients

hash:/etc/postfix/broken_clients:
    1.2.3.4/28 pipelining

        Wietse

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