Password complexity for domino webmail access

Hi All,I am lotus administrator,i have some issue in password complaxity for domino webmail users,right now we have not enable any ADS Sync. with Domino Server.But i need to implement the Password complexity on my Webmail Server.Passwords i need put like abc@123(Min 8 chars).

I don’t know how and where to add this on my domino webmail Access

Can some one guide me where to enable this feature or any free tool available on web.

Regards

AM