Xgen HAL Mail is a powerful free email client for Android.
Its improved features include:
* Push mail using IMAP IDLE
* Better performance
* Message refiling
* Email signatures
* Bcc-to-self
* Folder subscriptions
* All folder synchronization
* Return-address configuration
* Keyboard shortcuts
* Better IMAP support
* Saving attachments to SD
* Empty Trash
* Message sorting
* …and more