I noticed that e-mail notifications about new personal messages tend to end up in the Spam folder of my Gmail. Here's a direct quote from the latest one:
Why is this message in Spam? It is in violation of Google's recommended email sender guidelines.
It actually first happened like several months ago, but back then I just told Purvis and the problem was gone soon, so I assumed he cast a Command spell on Google staff and had them fix the issue. Alas, this seems to be a recurring problem.