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prd
Asked: 2013-08-28 19:52:32 +0800 CST

MAIL FROM command from postfix to mdaemon caused 501 Domain must resolve, but not on putty

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I have a strange problem with postfix. This first screenshot is captured by tcpdump on postfix. This one gave me "501 Domain must resolve" error.

I tried to connect manually, and enter information as captured on tcpdump on putty, but got different result.

Using putty, server responds as 250, Sender Ok

SMTP Server is MDaemon, and our mail server is Postfix

Any idea why it happened and how to solve it?

Thank you

postfix

1 Answers

  1. Best Answer

    Most mail servers allow different behaviour depending on who is connecting. This can be based on IP. It doesn't look like you are connecting from the sending mail server that is having problems. So you might expect things to be different. Try connecting from that server. Then check the IP Shield feature of MDaemon.

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