wmail is a Window Maker docklet watching your inbox, which is either a ordinary mbox or a directory conforming to qmail’s Maildir format. It provides a nice little GUI displaying some useful pieces of information about your inbox (as many other nice wm-apps doing nearly the same thing…). Per default it uses the $MAIL environment-variable to locate the inbox you are using, other mailing mechanisms like POP or IMAP are not supported - use a tool like fetchmail to retrieve POP- or IMAP-based mail.
For comments, see the original dockapps.org entry.
A newer version may be available in the Window Maker dockapps git
git clone https://repo.or.cz/dockapps.git
(View in browser.)