How to get rid of "The mail in ____ has been read." ?

[Russell Hoover <rusty@xxxxxxxxx>]

On a new unix account I have, if I set the MAILCHECK environment variable (in
~/.zshrc -- set there instead of ~/.zshenv to override the MAILCHECK setting
in /etc/zshrc), I get the following message when I exit my mailer (mutt):

"The mail in /home/2/r/rj/.mail has been read."  

(In fact I get it even if I don't set MAILCHECK, since MAILCHECK is set in
/etc/zshrc, the system's startup file -- I just get it less fequently then).

Since I'm using the maildir mailbox format in mutt, where each mail-message is
its own file, the message actually looks like this:

The mail in /home/2/r/rj/.mail//cur/916798766.10989_0.shell3:2,S has been read.
The mail in /home/2/r/rj/.mail//cur/916798766.10989_1.shell3:2,S has been read.
The mail in /home/2/r/rj/.mail//cur/916798766.10989_2.shell3:2,S has been read.
The mail in /home/2/r/rj/.mail//cur/916798766.10989_3.shell3:2,S has been read.
The mail in /home/2/r/rj/.mail//cur/916798766.10989_4.shell3:2,RS has been read.
The mail in /home/2/r/rj/.mail//cur/916842288.1278.shell3:2,RS has been read.

for however many messages are in my inbox.

Of course MAILCHECK also gives me the "You have new mail." message.

My question is, how can I get rid of "The mail in ___ has been read"
without getting rid of "You have new mail" ?

[shell3:~] uname -a
SunOS shell3 5.5.1 Generic_103640-23 sun4u sparc SUNW,Ultra-2
[shell3:~] echo $ZSH_VERSION
3.0.5

(I have a similar setup on 2 other machines and don't get this message.)

-- 
                              // rusty@xxxxxxxxx //