You don't need a mailing-list manager to run a mailing list -- some very
low-tech solutions do just fine, especially if your subscribership is stable.

If your list is moderated (i.e. you check that each message is appropriate
before distributing it to the list), all you need to do is maintain a list of
subscribers in your favorite e-mail program.  When a message arrives, you
forward it to the list.  Two hints if you do take this route: If your mail
program has a "bounce" function, you should use it -- that will preserve the
"From:" header indicating who originally sent the message, listing your
e-mail address as "Resent-From:", which is more appropriate.  You also should
consider putting your list of addressees on the "Bcc:" line rather than the
"To:" line, so that if people reply to a message it comes back only to you,
and not to the list (bypassing you and your moderation function).

You can set up a fully automatic mail reflector, if you're on a Unix system
running Sendmail, by using the Sendmail "alias" function (described well in
_Sendmail_, the O'Reilly & Associates "bat book").  If your system
administrator is willing to set up a special alias for your list, you can
maintain the list simply by editing the file to which the alias points, and
people sending mail to the alias will have their mail bounced out to the
whole list.  (Some systems include specific support for lists, i.e. DG/UX's
use of a "lists" directory for aliases as noted by <windigo@thepoint.com>.)
Be warned, though, that this approach has a lot of problems -- mailing loops
are a distinct possibility, and there's absolutely no control over who can
post to the list, or what they can post.  If you must have automatic
distribution of messages, you should look into using an MLM.