I had an idea, something that perhaps all of us can use. I don’t have the technical no how to make something like this, so I’ll just toss this out there. Maybe something like this already exists?
When someone send you a tell in game the add-on would prevent you from seeing it. From there the add-on sends a message back to the person giving them three options.

1. To flame/cry/complain about me reply 1
2. For general questions reply 2
3. To contact me directly press 3 (for friends only)

1 and 2 have different responses that you set; you can turn them on and off depending on your mood. Option 3 requires them to reply back with a password that you give out to friends only.