[PHP] Forgot Password Help?

I’m working for a client and they want to be able to recover their users passwords with a lovely forgot password script. They want the passwords to be emailed to them, I’ve already explained that using a password reset would be the best way of going about that. But nope they want the passwords to be sent to them.

I usually use a salted md5 hash for passwords and such, but it’s not reversible(well easily ;) )

I was looking at base64 but that’s not really an encryption as it is more of an encoding.

Does anyone have any suggestions on what to use?