My site is on Happy which is a recently upgraded cPanel server. Before the upgrade, I had SpamAssassin set with a subject rewrite so if an email got flagged as spam, I still got it but the email subject contained the word SPAM in it so my client could filter it. However, as part of the upgrade, apparently SpamAssassin was upgraded but it changed the way it did subject rewrites. The new cPanel Configuration panel does not allow you to write the header rewrite rule directly so that functionality is gone. So the default is dumping tagged spam emails into the spam folder on your account which you may or may not see in your email client.

After getting a couple of comments from people about whether I received their email, I did some digging with the help of LP support. Sure enough, there were over a dozen false positives dating back to Happy's upgrade date or so. Long headers didn't really indicate any good reason for the spam tag that I could tell. The good news was nothing was lost. The bad news is I had a bit of 'splaining to do about why I never responded to so and so.

Moral of the story is if you are on a cPanel server that got upgraded and you use SpamAssassin with subject rewrite, reconfigure it after the upgrade and keep an eye on your spam folder. The new and improved SpamAssassin is seemingly much more aggressive in default status.