Mail is stored in the user's individual mailfile.
The message is preceded by the sender's name and a postmark. If a user being sent mail is not recognised, or if mail is interrupted during input, the message is saved in the file dead.letter to allow editing and resending. Note that this is regarded as a temporary file in that it is recreated every time it is needed, erasing the previous contents of dead.letter . The mail utility tries to create dead.letter in the current directory. If that fails, it tries to create in the directory specified by the HOME environment variable.