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Reverse DNS Exchange 2010

I have an Exchange server 2010 with multiple domains.  The problem I have is some emails that go out would fail to a relay error.  I have my ISP setup a reverse dns but even with that it still fails to some selected emails that end users send.  

I tried to change my FQDN value i get a AuthMechinism on receiver connector error.  Can I have multilple FQDN so when other email server check my SMTP banner it replies correctly?  How is this all setup?

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Sajid Shaik M
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it's happening only with selected users ?... did u check from those selected users domain are u able to receive the email from other users ?

did u check at

what is the result it's giving ?
On Exchange 2010, the only FQDN that matters is the one on the SEND connector. Ignore the one on the receive connector, as that plays no part in the delivery of your email. You would only "fix" it to pass the test at mxtoolbox and the like, but it wouldn't make any difference.

The FQDN on the Send connector needs to resolve to your Exchange server and match the PTR on the IP address.

If emails are failing for users, what does the NDR say?

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I have multiple domains on my exchange server.  I originally had my ISP setup with all the domain for reverse DNS but I noticed it did a round robin so I switched it to just one primary domain that is important.  So my ISP resolves that one domain.  However, mxtoolbox fails and the response of the server SMTP banner is the domain I originally setup all the servers one.  So I think I need to change that banner but unsure how to do that.  I did try to make that one domain I want that the ISP resovles too as default but that didn't matter and still fails mxtoolbox.  

My challenge is to make every domain pass this reverse lookup.  but at first at least this one domain.

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Simon Butler (Sembee)
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I have the PTR record set correctly with my ISP.  Those email server that do reverse lookup still deny my emails.  
when I originally created my exchange server it is in a domain that all the other servers are in.  However, I needed to add an additional domain and have email accounts with that domain.  In active directory I have an OU for that domain and have that domain listed in the domains for my exchange server.   I am not sure why that fails.

Do I need to have a single exchange server for each domain that I need to support and make sure I have static IP assigned to each domain/exchange server?

There aren't enough IP addresses in the world for every domain to have its own IP address. Therefore no, you don't need a separate Exchange server for every domain.
Did you run through the tests that I outlined in my blog postings above? If your messages are being rejected, what does the NDR say?

I am still having this issue.  these things have not resolved my problem.
That doesn't really help provide you with a solution.
You have provided no information to assist. The contents of the NDR would be a huge help, but also indicating what you have done would be of some assistance.

I've requested that this question be deleted for the following reason:

didn't answer my problem
I do have a question.  BTW good article.  
will email get rejected on some email servers due to the inability to change the FQDN receive conector? since some email server verify SMTP banner for domain name to protect from what it may think as a relay?