Examine the header carefully. The header ends with the first blank line. The next header in the file will once again start with a From . From 's on the beginning of a line never exist within the body. If they do, the mailbox is considered to be corrupt.
Some mail readers store their messages in a different format.
The simplest way to send mail is to use the mail command. When you are finished, enter a . on its own on a single line. The username will be another user on your system. You can use mail to view your mailbox. This is a primitive utility in comparison to modern graphical mail readers but is probably the only mail reader that can handle arbitrary sized mailboxes.