Reset expired passwords

I’m looking for a solution for some of our users that VPN in. Most of the time these users just use OWA to check in, but every once in a while they have to connect to the VPN and then they find out that their password has already expired. Does anyone know of any software or solution that can enable these VPN users to reset their own passwords? Also, is there a way to notify them via email that their password is about to expire?