Post number function in SUBJECT

Googlegroups now offers the function of adding a post number to the
subject prefix.


http://groups.google.com/group/GROUPNAME/manage_post

Subject Prefix
The prefix will be added to all messages posted to the group. We
recommend surrounding the prefix with [ ], or { }. You can have the
prefix include the message number by adding the characters '%d'. Leave
this field blank to have no subject prefix.