Hi,
We would like to enable a user to subscribe to a list from a WWW page
dedicated to this list with minimal typing on his/her side.
Few questions arise in this regard:

1. Can one send commands to the listserv via the subject line?
2. How does the listserv know the name of the subscriber? i.e., which
   header field is used?
3. More generally, can one set a single button in an HTML file
   that would subscribe/unsubscribe to the list? Something of the sort:

<FORM ACTION="mailto:[log in to unmask] HOORA-L">
<input type="Submit" text="Subscribe">
</FORM>

Any hint will be greatly appreciated!
Moshe