Query on SMTP headers

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?
LVL 3
kam_ukAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

SteveNetwork ManagerCommented:
yes.. all mail servers will do a reverse lookup on IP address to ensure they are configured correctly.
0
bruce_77Commented:
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.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Email Protocols

From novice to tech pro — start learning today.