Best Mail Application iPhone

Hi there!
I have browsing for a few days for a better e-mail application, and I couldnt really find one that suits my needs...
Im guessing that I either havent searched thoroughly enough, or I the application just doesnt exist.
I am really in need of your advice for my situation, and please help me out.
I would need a mail application that:
1. has push notifications
2. is able to define and use templates
3. can search through all e-mail message bodies (iPhone Mail cant)
4. can sustain more than 5 accounts (GMail/Yahoo/Custom Servers) - I really like the iPhone Mail with its concatenated Inbox
5. filtering e-mail is optional
Any workaround would be also of use to me (several applications that by interacting with each other can do all this stuff).
Thank you in advance!
HT
MacBook Pro 15 Mac OS X (10.6.4)