The minimum length is five characters, far as I know.  Don't know about
max. length.  You may use any alpha-numeric characters, and most
punctuation and special characters.  Case is ignored (D1vC6r = d1vc6r =
D1VC6R) so don't bother with mixing upper and lower case letters.

Emphasize, *strongly*, that when entering their subscribed addresses that
they *must* enter their subscribed addresses, not what they think they are,
but what they actually are; [log in to unmask] (what he thinks his address is) is
NOT the same as [log in to unmask] (his subscribed address).  Only the
combination of the *subscribed* address plus password for *that* address
will work.  If they don't know what their subscribed address is, they can
do a QUERY listname.  If they then get a "you are not subscribed" response,
they contact you to fix it, please (they could do it themselves, if they
already have a password for the old address, but explaining all that, and
how to do it, is so much trouble that for address changes I just tell them
"contact the listowner(s)").

As Pete Weiss pointed out, email archive searches do not require a
password, *IF* they are sent from a subscribed address.  However, there are
not many folk left these days willing to do searching via email, even
though it is so easy and convenient (I do all of my LISTSERV searching via
email), so I wouldn't worry too much about explaining that.

Another thing to keep in mind is that if you have any subscribers who
receive list postings just fine, but the LISTSERV administrative stuff is
blocked (they cannot receive job outputs, confirmation messages, renewal
messages, etc.) they will NOT be able to search password protected
archives.  They can't get a password because they can't OK the password
confirm message, which they never receive.  They can't search via email,
which doesn't require a password, as the results are sent as LISTSERV
administrative mail, which they can't receive.  I have yet to talk any
of the sites which pass the list postings, but block the LISTSERV admin.
stuff into allowing the LISTSERV email through.

I sometimes wish, in such situations, that I, as listowner, could assign
a password for these subscribers, as they CANNOT get one for themselves.

Douglas Winship    [log in to unmask]