Back to the PTR RR:
$ dig +short MX bobhoffman.com 10 mail.bobhoffman.com. ^^^^^^^^^^^^^^^^^^^^ $ dig +short A mail.bobhoffman.com 72.35.68.59 $ dig +short -x 72.35.68.59 bobhoffman.com. ^^^^^^^^^^^^^^^
mail.bobhoffman.com != bobhoffman.com
Careful here. Email senders have nothing to do with MX records. Email receivers do.
I believe bobhoffman.com is the email sender in this case.
I would doubt this is an issue. Any split in/out mail server is going to have a different host for receipt (MX) than send.
-John