The RETRY command is used to retry sending your queued mail.  You need
never use the RETRY command, but if your mail to anyone is queued for
any reason and you are impatient, you can use this command to run MAIL,
which will search for queued mail sent by your login programmer name
and, upon finding some, make another attempt to send it immediately.

The RETRY command also retries sending mail TO you that was queued
because, for instance, you were editing your mail file at the time the
message was sent.

PLEASE DO NOT TYPE ↑C AFTER GIVING THIS COMMAND, OR YOU MAY LOSE A
QUEUED MESSAGE.

The remind phantom itself will automatically try about once every 3
hours to send queued mail.  If it finally gives up (after three days'
failures) it will both MAIL and SEND you a message telling of the
failure of the mail attempt.  An outcome of "expired" means the mailing
failed for three days.

For more information, see the file MAIL.BH[UP,DOC].