source: https://www.securityfocus.com/bid/10089/info
  
Multiple vulnerabilities have been identified in the application that may allow a remote attacker to carry out directory traversal and cross-site scripting attacks.
  
1st Class Mail Server version 4.01 is reported to be prone to these issues, however, it is possible that other versions are affected as well. 

http://www.example.com/AUTH=[some_value]/user/members.tagz?Site=www.example.com&Mailbox=[html_code]