Comment 2 for bug 266041

Here is a patch against the 2.1.5 Mailman release:

--- mailman-2.1.5/Mailman/MailList.py 2004-03-04 06:10:28.000000000
-0800
+++ mailman-2.1.5.patch/Mailman/MailList.py 2004-07-20 23:17:
09.000000000 -0700
@@ -1081,7 +1081,7 @@
         # It's possible they were a member of this list, but choose to
change
         # their membership globally. In that case, we simply remove the

old
         # address.
- if self.isMember(newaddr):
+ if self.getMemberCPAddress(oldaddr) == newaddr:
             self.removeMember(oldaddr)
         else:
             self.changeMemberAddress(oldaddr, newaddr)
@@ -1101,7 +1101,7 @@
             mlist.Lock()
             try:
                 # Same logic as above, re newaddr is already a member
- if mlist.isMember(newaddr):
+ if mlist.getMemberCPAddress(oldaddr) == newaddr:
                     mlist.removeMember(oldaddr)
                 else:
                     mlist.changeMemberAddress(oldaddr, newaddr)