In the last week, my client's emails have become lost, and finally found in the Apple Spam folder. What is Spam? Is it a flag coming from my ISP? I don't see any spam settings in Mail Prefs, and don't know how to change it, since it's an e-mail I've been responding to for years.
Thanks for your help!
Apple Mail 11.5 OS X 10.13.6 High Sierra