[Mailman-Users] Ignoring username+ at whatever.edu addresses?

[Mailman Mailing List Manager]

Hi folks,

I have one mailing list on my system that has a lot of users from a nearby
university where they use a funky username+ at whatever.edu addressing scheme.
Their mailer seems to randomly send email either with or without the +.  Is
there a way I can tell mailman to ignore the + at the end? 

Steven J. Owens
mailman at darksleep.com