Without doubt the fastest is the keyboard shortcut. If you used Netscape before, you'll have to get used to it.
Compose a New Message Quickly in Opera
To open a new message composition window in Opera:
- Press Ctrl-M (Windows, Linux) or Command-Option-M (Mac). (Think message.)
- In Opera 6 and 7, press Ctrl-E (think email).
(Updated August 2012)