[Mailman-Users] Edit rejection notice text

Is there a way to edit the text contained in _non-member_ rejection notices?

I.e., if a non-member posts to a list and the Action to take for postings from non-members for which no explicit action is defined setting is set for reject, this is what the user gets:

"You are not allowed to post to this mailing list, and your message has been automatically rejected. If you think that your messages are being rejected in error, contact the mailing list owner at xxx@dom.ain."

Where is this template at? I've searched through the archives/en directory and can't find it.

Thanks!

Todd