Last week it seems like Google changed their group (Google App’s groups) spam settings and it shutdown most of one of our client’s internal emails to their groups.
We trouble-shooted the email headers, and saw a SPF softfail, but also a link to the new Google groups spam policy. After talking to Engineering over at Google, it became clear that a DKIM setup was necessary to prevent this.
We logged into Google Apps management to generate the public key and then setup the DNS, using the tool at DNS Watch to generate a parallel entry for testing. It’s fixed!