Sprint Mobile Email vs regular ol' direct push?

[leadpoizon]

I realized that when I was on the Touch, Sprint offered the mobile email application which was an awesome application that not only didn't show up in your running processes, but didn't leave the data connection active. Since I have come to the PRO, I realized that services such as SEVEN (even though it's the same company that designed both softwares) use Push by keeping the data connection active. This is actually how the real direct push from the Exchange server works too. The question is here: How is Sprint able to keep the data connection closed and still have push email?! And doesn't leaving the data connection open at all time cause a great drain on your battery life?

(I used to also have a .cab for mobile email that worked on the PRO, but lost it. T_T)