Well, it looks like Google just updated their system to be more strict and now it won't accept incoming emails with a FROM address that doesn't match the domain sending the email.
The only solution appears to be to either:
1) Use a @mycafecommerce.com FROM address like: firstname.lastname@example.org
You could use a signed email from to hide it a little like: Volleyball Registration <email@example.com>
2) You could point your main domain to our server so that you can use the domain in your FROM address. It looks like your main domain is just a page with a link to facebook and to your store. If it went to your store you could add a link to facebook on your home page.