4/16/2014 Mail Delivery for Outbound Postini Issue

Google has reported that mail sent outbound via Postini to Proofpoint hosted domains is not being delivered as of 11:23 am EST.   Messages may be deferring with a 451: cannot connect to domain:<recipient domain> - psmtp" error code or bouncing with "550 MX records inaccessible for too long for domain: <recipient domain> - psmtp".

This appears to be an issue with the recipient domains' DNS servers, but Google engineers are investigating.

You can view the report and updated status from the Known Issues page in the Google Enterprise Support Center. We will also keep you updated as more information becomes available. 

Update: Issue is resolved. Mail should now delivery correctly to the domains that are hosted on Proofpoint.