There are many mailsystems like hotmail,yahoo but none of the big mail systems(to my knowledge) function with java mail API.can any one tell why.
First of all, Mail program uses SMTP and POP3 concepts.
A mail program needs to talk with lower level of the TCP/IP stack. But the artitecture of the Java prevents from talking to these levels. This is where c++ and C takes major advantage as they could use system calls directly.
But to add, Java recently came with an upgraded version of Mail package.(i don't know much abt this..)
SMTP and POP3 use sockets which are at the top of the stack, hence Java may interface with these without problems, since it supports socket communications.
The only software that uses lower-level functions in the stack are network control and diagnostics programs, here C and C++ may have an advantage.
It's true! The problem with Hotmail is that it uses HTTP; As far as Yahoo! is concerned, you can access it with JavaMail API (POP3 and SMTP) as long as you make some modifications to your Yahoo mail account, that is if you go to preferences and choose to have access via POP3 and SMTP, in Preferences/POP3- well you'll see.