[Mailman-Users] How can i make a list public so people who are not subcribed can send a message?

Greetings -
Well, as I said in my message...
"You can use regular expressions here if you wish."
:-)

If you click the "(Details for accept_these_nonmembers)" next to the
text box you'll see a little additional help, which says:

"Postings from any of these non-members will be automatically
accepted with no further moderation applied. Add member addresses
one per line; start the line with a ^ character to designate a
regular expression match."

Thus rather than using the limited glob-style pattern matching such as
*@custo.dom
you instead use full regular expression pattern matching such as
^.*@custo\.dom$

If the local part of the sender addresses (the bit to the left of the
"@") follows a set pattern for all the customers who can send to the
list then it might be possible to model that too. For example, if
the local part for each customer was of the form "initals.surname"
then you might like to try something like:
^[a-z]+\.[a-z]+ at custo\.dom$
and thus prevent postings from "joe at custo.dom" (because "joe" doesn't
match this format).

You will need to read up on the syntax used for these regular
expressions. For example "." means "any one character", whereas "\."
means "the single character which really is a '.'"

Cheers,
Mike B-)