Mysterious “You have new mail” in OS X Terminal

Recently I discovered a mysterious message showing up in every new Terminal window I opened under OS X. The notice simply read “You have new mail”:

First I thought this was something that had been put in the Terminal’s startup message (called motd – Message of the Day, which can be edited with “$ pico /etc/motd”). However, this was not the case.
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Fortunately a short web-search delivered the answer and solution to this strange occurrence: the message is a part of the built-in Unix mail processing system, called “mail” or “mailx”.

This application provides a functionality called “sendmail” which is commonly used in website development to generate an e-mail, for example in a contact form. And this was also the reason why I had that suspicious mail notice in my Terminal.

How to get rid of those messages

By using the follwing Terminal command, you will receive an overview of the mail messages – namely the mail inbox:

$ mailx #launches the unix mail app
Mail version 8.1 6/6/93.  Type ? for help.
"/var/mail/user": 1 message 1 unread
>U  1 MAILER-DAEMON@...  Mon Feb  8 21:41  81/2505  "Undelivered Mail Returned to Sender"
?

The prefix “U” stands for “Unread”. There are other prefixes such as “N” = New and “> ” = Read.
From here you can use now several commands to handle the messages (display the list using “?”):

? ? [RETURN]

Command

Description

t

type messages

n

goto and type next message

e

edit messages

f

give head lines of messages

d

delete messages

s

file append messages to file

u

undelete messages

R

reply to message senders

r

reply to message senders and all recipients

pre

make messages go back to /var/mail

m

mail to specific users

q

quit, saving unresolved messages in mbox

x

quit, do not remove system mailbox

h

print out active message headers

Most commonly you might want to read the message(s) and/or delete them. To do so, type:

? message-id [RETURN]
#Use ctrl+v to skip through the message

Afterwards simply use the following command to delete a message:

? d message-id [RETURN]

Further reading

1. Type $ man mail into the Terminal
2. History of mail, Mail, mailx & nail
3. mailx & mail on Wikipedia