Emails not going through

I have a form setup to capture an event registration. (http://nadp.net/register)

When I submit the form, it seems to go through, but I am not receiving the email to the address that I put in the “To:” field under “Mail”.

I have tested with several different emails that I own, and they all come through except for any email that shares my domain: nadp.net

I have noticed the same thing happening with a Contact 7 form that I created on another site, http://mtabolitionco.org/signup/

The email goes through to any email except any one at mtabolitionco.org.

Both nadp.net and mtabolitionco.org use google apps as their mail server.

http://ww.wp.xz.cn/extend/plugins/contact-form-7/