Typing German Umlauts in Mail

On a U.S. keyboard, it is option+u, then press the letter u which produces ü. You can also press and hold the letter u, and an array of accents will appear above it, and on the previous keyboard, you can type 2 to select the ü.

In order to get the automatic accents to come up when you hold down a key do the following:

In Terminal enter:

defaults write -g ApplePressAndHoldEnabled -bool true

Reboot required to activate

Change true to false to turn off

Then when you hold down a key é you get this.

Hit the number key to select the umlaut you want or use the cursor.