How do Google,Yahoo and other top level mail services secure passwords?
What technology they are using for securing and storing passwords?
How do they manage mail passwords ?
Well I don't believe that any of us can say definitively what any of those companies are using, but it is highly likely that all of them are using some form of one-way hash to store the passwords. Using any other type of password storage would be highly irresponsible. SHA-1 and MD5 are frequently used for this type of hashing.
As far as what they're using to manage passwords, it's probably safe to say that they're all using a custom-built account system that interfaces with their back-end mail delivery and transport systems.