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Query on SMTP headers

Posted on 2009-05-08
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Last Modified: 2013-11-30
Hi Guys

When I check the message headers of an email, I see text such as this:

Received: from mail.mydomain.net ([83.170.88.1]) by bay0-mc5-f6.bay0.hotmail.com

How are these values worked out? I expect Hotmail knows the IP. 83.170.88.1, that is connecting to it, but how about the hostname, mail.mydomain.net? Is that what is mentioned in the EHLO, or does the Hotmail server carry out a reverse DNS check on that IP address?
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Question by:kam_uk
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2 Comments
 
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by:Steve
ID: 24335597
yes.. all mail servers will do a reverse lookup on IP address to ensure they are configured correctly.
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bruce_77 earned 500 total points
ID: 24402428
That is how the SMTP client announces itself to the SMTP server...so - yes - in the EHLO/HELO SMTP command.

The SMTP server doesn't form this value from a rDNS check.
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