Only receiving from Webmail

[Wazz]

Hi,

My exchange server is not receiving emails from addrsses apart from hotmail and gmail. Emails from other locations, like other domains and companys are not getting through. This has started since a business router has been changed and I am sure its a routing problem, any ideas how I can fault find this?

Additionally, I have just checked my domain on mxtool box, Reverse DNS does not match SMTP Banner. Is this a possile cause of the problem?

Is the way hotmail/gmail send there emails different to other exchange clients. Could it be a protocol which is being blocked etc

Thanks
Wazz

 

[Zelandakh]

Hey Wazz,
From outside your firewall, telnet on port 25 to your IP address then:
helo remotetest.com
mail from: test@test.com
rcpt to: wazzRealEmailAddress@WazzRealDomain.com
DATA
Subject: This is a test

.

That should send a test email.
Then repeat with the FQDN of your Exchange server

Reverse DNS not matching the SMTP banner should be irrelevant but worth nothing.

Hotmail and Office 365 getting through could suggest they are using port 587.

Expectation:
The new router does not have port 25 open to the Internet and piped to your Exchange server's internal IP.