RCV is a program which allows you to examine messages sent to you by
the MAIL command, choosing for each message to delete it, print it,
etc.  To use it, type RCV to the monitor, and say "?" whenever you
are asked a question you don't understand.  NOTE: To exit from RCV,
type "E"--not <call>--to avoid losing some of your mail.
For more information, type "TYPE RCV.BH[UP,DOC]"

Since mail files are now by default in E-format, you may want to use
E to edit your mail file.  Do so (at a display terminal) by typing
  ET ∂
E is much more useful than RCV for reading mail from a display terminal.