[Mailman-Users] Add Auto Number to the subject's prefix

[Wang wei]

hi all:

I just use the Mailman 2.1.5 with CJK codes supported.
And I has a problem here
How to add Auto Number in the prefix of the Subject
For example:
 mailman-users at python.org 's subject prefix is [Mailman-Users]
 and I want to add the Auto Number looks like this  [Mailman-Users:000001]
 when next mail comes the subject would be [Mailman-Users:000002] ...

Does someone know how to do this?
Thanks a lot