454 5.7.1 Error - Outbound emails getting bounced

Error message:
454 5.7.1 DXNS3 1.2.3.4: Message refused. Your host name dosen't match with your IP address: EX1SERVER.domain.local If you need, please contact stamp@daumcorp.com.

We have been getting mail bounced back from a lot of outside mail servers. To fix it, I have removed the SPF record but don't think that is the issue.

We asked our ISP to change the PTR record for 1.2.3.4 to reflect as mail.domain.com.


Question:
Why do outside servers see us as EX1SERVER.domain.local if we have changed the PTR to show as the mail.domain.com address?


I looked here but didn't have direct info regarding my issue:
http://www.experts-exchange.com/Networking/Misc/Q_25518074.html
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Paul WagnerFriend To Robots and RocksAsked:
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Alan HardistyConnect With a Mentor Co-OwnerCommented:
Your SEND connector FQDN should be mail.domain.com as that is what is used to verify you are who you say you are.

When a server receives email, they check your FQDN, confirm that it resolves to the IP Address you are sending from and then reverse check by making sure that the IP address you send from resolves in DNS to the FQDN and if it matches, it continues to listen to your server sending the email, otherwise it can reject your communication for being improperly configured which looks like what is happening here.

Are you sending out from the same IP Address that you receive emails on?

Alan
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Tony GiangrecoCommented:
This normally means you have to check the "My outgoing server requires authentication" box on the Outgoing Server tab of the "More settings" dialog of your account.

Since this is from the Exchange server, you probably need to adjust the authentication level and may need to use a secure port.
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leHazardCommented:
Another possibility to try is to look at the client configuration. If the client is authenticating to EX1SERVER.domain.local (as the server name) then this will be attached to each message. If the message says it was sent through  EX1SERVER.domain.local but the DNS says it came from mail.domain.com, the client configuration should be causing the problem. Assuming you allow outside authentication, I would change the client to authenticate to the external name, which might solve the issue as well.

If these are server errors, this should solve the issue. If the errors are in the email client than the other suggestion should work well.
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Paul WagnerFriend To Robots and RocksAuthor Commented:
Are you sure that's all it is? We currently have authentication required for our server.

I was looking at this field in the Send and Receive connectors:
Specify the FQDN this connector will provide in response to HELO or EHLO

Should I have that listed as mail.domain.com? It's currently listed as EX1SERVER.domain.local
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Paul WagnerFriend To Robots and RocksAuthor Commented:
Changing send connector to reflect mail.domain.com cleared the issue right up!

Sorry it took so long to get back to you guys. I wanted to test long enough to make sure the problem truly went away.

Yes, the outbound is the same as inbound.
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