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Re: Strange conversion of 5.2.2 into 4.1.0 error

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  • Viktor Dukhovni
    ... RFCs have bugs, this is one of them. In practice MTAs don t return 552 for too many recipients , and the 552- 452 mapping creates more problems than it
    Message 1 of 5 , May 3, 2013
      On Fri, May 03, 2013 at 02:25:15PM +0200, Ralf Hildebrandt wrote:

      > Section 4.5.3.1 of RFC 2821 (4.5.3.1.10 in RFC 5321) recommends to treat
      > a 552 response after the RCPT TO command as if it was actually a 452
      > response. This behaviour was intended for cases where the number of
      > recipients exceeds the MTA's limits, and the idea was that the sending
      > MTA should requeue the extra recipients.

      RFCs have bugs, this is one of them. In practice MTAs don't return
      552 for "too many recipients", and the 552->452 mapping creates more
      problems than it solves.

      > Section 6.4 of RFC 1870 contradicts this, and explicitly says that a
      > 552 response must not requeue the recipient. This is intended for cases
      > where the message size limit is imposed on specific recipients.
      >
      > So generally, the smtp response code 552 can be used for multiple
      > incidents, like the recipient count and also for the message size. In
      > order to address this kind of issue on the Email Security appliance, we
      > have logged a 'defect' with number ...... "Per-recipient rejection based
      > on message size in response to a RCPT command", and our engineering team
      > is working on an implementation which works in all cases that all
      > messages get soft or hard bounced correctly without any issues.

      In the interim you can use 554 5.2.2 ... which won't be misunderstood.

      --
      Viktor.
    • Ralf Hildebrandt
      ... Yeah, I ll do that instead. -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64 Franziskanerstraße 15, 81669 München Sitz der Gesellschaft: München,
      Message 2 of 5 , May 3, 2013
        * Viktor Dukhovni <postfix-users@...>:

        > In the interim you can use 554 5.2.2 ... which won't be misunderstood.

        Yeah, I'll do that instead.

        --
        [*] sys4 AG

        http://sys4.de, +49 (89) 30 90 46 64
        Franziskanerstraße 15, 81669 München

        Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263
        Vorstand: Patrick Ben Koetter, Axel von der Ohe, Marc Schiffbauer
        Aufsichtsratsvorsitzender: Florian Kirstein
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