Huge entries in /var/log/maillog for vchkpw-pop3

I have a huge entries in /var/log/maillog

It is about vchkpw-pop3 like these one :

Mar 29 23:24:44 padawan vpopmail[7296]: vchkpw-pop3: (PLAIN) login success xxx@xxx.com:00.000.000.91
Mar 29 23:25:35 padawan vpopmail[8109]: vchkpw-pop3: (PLAIN) login success xxx@xxx.org:00.000.100.36
Mar 29 23:26:50 padawan vpopmail[8195]: vchkpw-pop3: (APOP) login success xxxx@xxx.com:00.0.110.98
etc…

What is there these entries now ?
How to stop them ?

Thanks
Pascal

See this thread too, Pascal:

http://interworx.info/forums/showthread.php?t=485

JB