Reverse DNS does not match SMTP Banner

bannerexchange-2007smtpsonicwall

I had this Warning with mxtoolbox. I know that it's not necessarily a big problem, but since we are having lots of issue with email delivery, I want to check everything.

I have a Exchange server 07 + Sonicwall.

My FQDN is office.mydomain.ca for send/receive connectors.
When I try : telnet office.mydomain.ca 25 –> 220 MYSERVER.mydomain.local Microsoft ESMTP MAIL Service ready at Fri, 7 May 2010 10:34:36 -0400

I can change my SMTP Banner in the Sonicwall, but I don't know what to write, if there is a specific syntax or what can be the consequence if it doesn't work.

Thanks for your help.

edit: Here's the result for the SMTP test:

220 emailsecurity.mydomain.ca ESMTP
SonicWALL (7.2.1.2841)

Not an open relay.

0 seconds – Good on Connection time
0.296 seconds – Good on Transaction time OK – xxx.xxx.xxx.xxx resolves to
Warning – Reverse DNS does not match SMTP Banner

Session Transcript:
HELO please-read-policy.mxtoolbox.com
250
emailsecurity.mydomain.ca [78 ms]
MAIL
FROM: supertool@mxtoolbox.com
250
2.1.0 MAIL ok [62 ms]
RCPT TO: test@example.com
550 5.7.1 Unable to
relay for [78 ms]
QUIT 221 2.0.0 Bye [62 ms]

Best Answer

In the SMTP service of Exchange there is a special setting to override the hostname exposed by SMTP server during SMTP greeting. I think it is inthe same window of the smart host setting (sorry I don't have an exchange server at hand right now)

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