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Re: postfix as incoming relay to protect exchange server / recipient lookup

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  • Martin Kellermann
    ... yes, thanks ... we did already. every parameter is well documented - and after i read the postfix-manual-pages it s meanings are easy to understand :-)
    Message 1 of 30 , Dec 6, 2010
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      Am 05.12.2010 20:40, schrieb DTNX/NGMX Postmaster:
      > On 02/12/2010, at 23:08, Stan Hoeppner wrote:
      >
      >> Martin Kellermann put forth on 12/2/2010 6:08 AM:
      >>
      >>> and there's a 5 sec. delay ... seems way too long to me for just
      >>> checking the recipient...!?
      >> That delay should be no longer than what a typical delivery to the
      >> Exchange server would be. Since no message is sent, it should be
      >> shorter by quite a bit. I would guess the delay is within the Exchange
      >> server, not Postfix, so you may need to do some sleuthing on the Exch
      >> server to see what it causing the delay.
      > A testing tool like 'swaks' is great for testing RAV and other SMTP transactions;
      >
      > http://jetmore.org/john/code/swaks/
      >
      >
      >>> PS: should unverified_recipient_reject_code set to 450 or 550 ?
      >> You should probably leave this at the defaults. As I understand it, the
      >> default configuration will return a 5xx for "unknown user" and a 4xx if
      >> the query fails, due to network, etc.
      > The default is '450' for both unknown users and transient errors, see;
      >
      > http://www.postfix.org/postconf.5.html#unverified_recipient_reject_code
      >
      > From the same page: "The unverified_recipient_reject_code parameter specifies the numerical response code when an address is known to bounce (default: 450, change into 550 when you are confident that it is safe to do so)".
      >
      > We also found it very handy to set up our 'notify_classes' parameter, so the postmaster (or any other user you configure) gets a transcript of the SMTP session when Postfix rejects mail. Note however that this adds load and can generate a large volume of messages to the postmaster. It works for us at our current volume, YMMV.
      >
      > Lastly, you may want to set a value for 'unverified_recipient_reject_reason' if you don't want to share the details of the backend server, such as hostname and/or IP address, with the outside world.
      >
      yes, thanks ... we did already.
      every parameter is well documented - and after i read the
      postfix-manual-pages it's meanings
      are easy to understand :-)

      setup works now as expected and we started a test-run to see how
      performance on exchange
      side and how big the SMTP-overhead is...

      thanks again for all your effords and contributions.
      > Cya,
      > Jona
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