source: https://www.securityfocus.com/bid/10782/info

It is reported that VPOP3 is reported prone to a remote denial of service vulnerability. This issue presents itself when an attacker issues a URI request containing a large value for the 'msglistlen' parameter to the web mail interface.

VPOP3 2.0.0k is reported prone to this issue, however, it is likely that other versions are affected as well.

http://www.example.com:5108/messagelist.html?auth=MDA4MDA2MTQ6MTI3LjAuMC4xOmRpbWl0cmlz&msgliststart=0&msglistlen=10&sortfield=date&sortorder=A