I have the same problem; and I think: My letter is too long, or too short, I have written something that my pen pall hate, or that remember something of ugly that happened in the past. But the real Difficulty there is "What you put in the stamp, that not hurt your pen pal! This is the real Issue!

There are already a bunch of versions of this in the suggestions and Slowly as even aggregated them into a single group suggestion. Here's hoping it finally happens.