How do you turn the envelope icon off?

[d.b.wood]

The icon goes off after smgr checks your /usr/mail/<logname> file and
concludes there's no mail there.  Either no file at all, or file size
zero will keep it off.  Also, clicking on the envelope icon gives smgr
a time to compare with the mail file, and the icon stays off until the
modification time of the mail file is more recent than the stored
"last-click" time.

You can use any mailer to read your mail, and smgr will eventually get
the idea.  There's no message counter.

Dave Wood