I realized today I wasn't getting mail notifications, and I hadn't set them up on this shell. So here are some things I do on my local machine that work here:
To get the shell to tell you when you have new mail, after command
executions, add this to your .profile or your $ENV files
(or other shell RC file) in your home directory.
export MAILCHECK=0
And, if you want, you can have a persistent notification when
you have un-incorporated mail, or more specifically, when your
$MAIL (/var/mail/$USER by default)` isn't empty.
PS1="$(test -s $MAIL ] && echo '* ')$PS1"
For maildir try this:
PS1="$(test -n "$(ls -A $HOME/Maildir/new)" && echo '* ')$PS1"
This works in /bin/ksh, I can't speak for other shells.
If anybody else has some quick tips they would like to share, I encourage them to edit this page.
Happy Unixing!