javax has a base 64 method. certainly for the mail class. failing that use
google and writer your own.

hi search in net for source forge base 64 u will be getting a
java file use that .That code is very good thats is into production for us now

Concerning the base64 format, as far as I remember, cause I have used his
package along time  ago, in the same class, there's a method called encode(). If
it's not in the same class, I think it's in the package. This method returns the
original string. I am sorry that I don't remember its exact location, but, it's
there. just look fo it.