This is what I send to some of my lists (educationally oriented) on a
semi-annual basis.  Feel free to modify (change zzzzzz-L and hostnames)
to your needs ...

Dear Fellow zzzzzz-Lers:

It appears to be that time of the year again when you either know someone
who should subscribe, or are leaving/retiring from zzzzzzzzzz.  To assist
you, we provide the following fast-paths.

To UNSUBSCRIBE via email, just send a blank message (by click and send) to:

mailto:[log in to unmask]

To SUBSCRIBE via email, just send a blank message (by click and send) to:

mailto:[log in to unmask]

There is no subject or body-of-text needed.  LISTSERV will send an email
back to you and ask for a confirmation of the subscription request.  Use
your email REPLY function, and send back an OK on the first line of the
reply email message.  That's it.  LISTSERV will subsequently reply with
an acknowledgement that you are subscribed.

Of course, if you have difficulties e.g., such as your original
subscription address having changed, please feel free to get in contact
with us for assistance using the preferred address:

     mailto:[log in to unmask]