Imagine a time before instant communications, where you have no idea how life has treated the recipient since you last saw them and it might take months for your letter to arrive. It is a sincere hope that they are well and that tradgedy has not befallen them.
It would be neurotic and unreasonable if your last update on their life was only days or even hours before, but in the days of letters hope is really all you had. It's just honest.
Oh god, I really hope my phone doesn't do that when it records. The recording button is on the screen during calls and I accidentally hit it all the time.