I tried sending an email from gMail to my account email, to test if it was working correctly, this is the message I received:

This is an automatically generated Delivery Status Notification

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

Delivery to the following recipient has been delayed:

bob@site.ext

Message will be retried for 2 more day(s)

After two days, I received a new message:

This is an automatically generated Delivery Status Notification

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

Delivery to the following recipient has been delayed:

bob@@site.ext

Message will be retried for 1 more day(s)

And finally, three days later:

Delivery to the following recipient failed permanently:

bob@@site.ext

Now, the technical details gMail gave me was this:

Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 451 451 Temporary local problem - please try later (state 14).

I don't know what this means exactly. Is my web-host blacklisting Google? Is my account not correctly configured? How should I configure it correctly if it isn't? Tips? Ideas? Web-host support? I sent it in.