The mail is kind of hit or miss. Some days it can be very easy with light loads and some days it can be a lot of work (sometimes requiring extra runs to get all the morning mail to ACK). Around the holidays and summer is when the loads are at their peak. I've never held a mail line but I was checked out to fill in on it last year when I was a PIC and I've filled in on it a few times in the last month. I like doing it but I wouldn't want it as my fulltime line. I know right now they are having some of us SVT (backup/reserve) captains fill in because there is only one PIC doing it right now, normally being two or three mail pilots.