Shortcut keys

The tooltips of some commands do not show their keyboard shortcuts (like for instance “Attach File”).
Do I always have to use my mouse for this or are there any hidden shortcuts for or can I create my own?

While not all commands in Outlook have their own direct CTRL+<key> shortcut, they are all still accessible via a keyboard sequence. The difference is that instead of pressing multiple keys at once to initiate the command, you press them after each other instead.

When you are in the main Outlook screen, the keys to press are indicated by underlined characters.
When you are in an area that has the Ribbon (like when creating a new message), the keys to press will float above the options.

To start, you must press the ALT key once (you can release the key directly, you don’t need to continue to hold it). Then type the characters one after the other to select the option that you want.

Example for opening the Options… dialog from the main Outlook interface:
ALT, t, o

Example for attaching a file from the New Message screen with Ribbon in Outlook 2007:
ALT, h, a, f

Note: in the main Outlook interface, it could be that several options hold the same underlined letter to press. This often happens when you add more commands to the Outlook Toolbar yourself or via an addin that installs its own toolbar with shortcuts key. When that is the case, you can press that letter again to switch to the other option with the same letter. When the correct option is selected, press ENTER to activate it.