[CentOS] DKIM

> 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