Reverse DNS on Exchange 2010

Hi
I have two exchange 2010 servers:  x.x.x.72 and x.x.x.73
I have a reverse DNS ptr record for both of these machines pointing back to mail.mydomain.com

My users are getting an error message when they try to send mail to a craigslist.com address.
The error I see in the log is:
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mail.mydomain.com [x.x.x.73] Please setup matching DNS and rDNS records: http://www.craigslist.org/about/help/rdns_failure
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I have an A record [mail.mydomain.com] pointing back to .72
BUT I don't have an A record pointing back to .73.

So, I'm wondering is that what I need to do, create another A record and point .73 back to mail.mydomain.com?

I was concerned having two A records pointing back to the same  mail.mydomain.com. I wasn't sure if that would cause any problems.

Or should I create a send connector on .72 and only allow mail to be sent out for craigslist.com?

As you can see, I'm unclear on the best way to solve this.

Any advice is welcome.
Thanks!
LVL 1
nachtmskAsked:
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footechConnect With a Mentor Commented:
If you're sending out from both IPs, then you should have separate A records (with different names) for each of them.  And the PTR record for each should reference the name in the matching A record.
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nachtmskAuthor Commented:
Thanks footech.
I just realized that before I read your response.
Nacht
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footechCommented:
Glad you worked it out.  In case you're wondering, this is known as forward-confirmed reverse DNS.
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nachtmskAuthor Commented:
Is changing the SMTP banner on the second  mail server needed?
Thanks again!
I didn't know that was the name for it.
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footechCommented:
From what I've seen, not as many people check your SMTP banner, but yes it is good practice to have the banner match the name used for the matching DNS records.
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