Did you catch the death of Postini?
According to Google, all mail stopped flowing through Postini servers on June 15.
Any Postini clients who had not made the transition by the end of May were supposed to have been forcibly transitioned then.
Postini was a traditional troublespot when it came to deliverability. That shouldn’t be the case anymore.
- Postini Transition to Google Apps, Google (n.d.). Retrieved June 25, 2015 from http://postini-transition.googleapps.com/.