I used to write rejection emails for companies at the end of YC interview days. It always sucked, especially when it was borderline decision (which it often was) but PG made doing these well an important part of internal YC culture. We couldn't leave until they were finished and each one was reviewed by another partner before sending.

In hindsight I'm glad we did this. In the years since I've had multiple people tell me the rejection was a positive turning point and the only honest feedback they'd received.