I am using version 22.214.171.124
My wordpress installation is not on hostgator but the domain specific email related to the domain name is on hostgator.
The email account is able to receive messages sent from virtually any address accept the contact form.
In testing I have defined the custom from address so that the from and return path addresses match and confirmed that we have the correct spf records.
If we cc or bcc the message to a gmail or google hosted apps or domain specific yahoo email account the message is successfully received and in reviewing the message header it gets an spf pass in all cases. However, with hostgator nothing and no bounced messages.
I contacted hostgator and they swear it is a problem with the form and not with their email.
My gut says that hostgator's mail server is vaporizing the message at the mail server level for some reason.
Have you heard any issues related to hostgator mail receiving contact forms? Any suggested solutions/work arounds?