[Mailman-Users] mail from localhost

[AxL]

    Hrm...everyone on the mailing list gets mail fine, but sometimes
their mail is held up for approval. The users are all subscribed as,
say, "joe at frodo.university.edu", "bob at frodo.university.edu", etc...but
sometimes the mail header comes out as "Received: (from joe at localhost)",
which is held for approval, since that isn't what is listed for the
subscriber's e-mail, nor should it.

    Is this a problem with mailman or with the site?

-axl

PS - Turning on access so non-members can post to rthe list is not
desired, in this case.