Choose the device for which you want to download Mail for Exchange. If your device is not listed here, your device does not support Mail for Exchange.
If you are using a supported S60 device simply follow these steps to obtain the application:

1. Go to Menu > Download! on your device

2. Go to the Search function and enter ‘Mail for Exchange’

3. You will be led directly to the location of the application
For a list of compatible devices, see Mail for Exchange, Compatibility: http://europe.nokia.com/find-products/nokia-for-business/messaging.