Exchange 2010 and reverse DNS

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:
----------
mail.mydomain.com [x.x.x.73] Please setup matching DNS and rDNS records: http://www.craigslist.org/about/help/rdns_failure
---------------

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!
Mike