What does dead.letter files do

Question

I find dead.letter files from time to time in my $HOME directory. What they are for?

Answer 1

Either a program tried to send mail and failed (this is more likely), or you were in the middle of writing mail and broke out, so the client saved the draft in dead.letter. From the mail man page:

Normally, when you abort a message with two interrupt characters (usually control-C), mail copies the partial letter to the file dead.letter in your home directory.