I mainly use Google’s mobile Gmail application on my E71 for my email needs. I’ve just heard that the application has been upgraded to version 2, and is considerably improved.
Also, users of Yahoo! Go will be pleased to know that version 3 has now been updated to work on the E71. Yahoo! Go is definitely worth installing if you use any of Yahoo’s services. I’m a long-time Flickr user, and Go’s Flickr interface is gorgeous – ideal for passing the time when you’re stuck on a train or bus. You can even upload photos from your phone. Yahoo! Go can also connect to the E71’s GPS and give you location-based information if you’re out and about and want to find things to do or places to eat.