Here's how to set up push email for GMail on the T-Mobile Dash:
- Log into https://my.t-mobile.com and click "Set up my email". Set up your GMail account there and enable alerts for new mail.
- On your Dash, open Messaging and add a new account. Use "Other (pop3/imap)" for the provider.
- Follow the wizard. Use POP3, name the account GMail.
- The pop3 server should be myemail.t-mobile.com; require SSL. Use the username specified on the my-tmobile email page (under settings / mailbox / pop settings) (probably [yourphonenumber]:1) and your gmail password.
- Use smtp.gmail.com for the outgoing mail server. Require authentication, require SSL; specify alternate credentials as [username]@gmail.com and your gmail password.
- On the Dash, Start / Set Up My E-Mail / Configure my E-Mail Triggers / Enable Automatic E-Mail Updates should be checked for the GMail account.
That should do it. There are two tricks: first is to use T-Mobile as the intermediary for incoming messages. They send a "silent SMS" which triggers the GMail account to send and receive. The second is to use GMail's own SMTP server so that outgoing messages get saved in your GMail account (T-Mobile's SMTP server doesn't push it back to GMail). No more polling through POP3, no more crappy Java applet, no more mobile web-based interface. Enjoy the bliss!
Edit: I should mention that there's an up to fifteen minute delay on the push. It looks like T-Mobile polls GMail over POP at about that interval and pushes updates to the Dash when they occur.