I've an [email protected] email address which receives emails from clients and delivers it to various people within my company. However, since today I get the following bounce error message when sending an email to this address:

Delivery to the following recipient failed permanently:

[email protected]

Technical details of permanent failure: Message rejected by Google Groups. Please visit http://mail.google.com/support/bin/answer.py?hl=en&answer=188131 to review our Bulk Email Senders Guidelines.

The Bulk Senders Guidelines describe how to send out bulk emails. However, in my case I only receive one email and distribute it to a couple of people within my company. Same problem applies to the [email protected] email address which we use internally.

Does anyone know how to resolve this issue?

UPDATE: I just realized that emails coming from the outside and being sent to this address still work. It just seems to be emails coming from my domain. I found a solution and posted it below.