You might also consider using AppleScript.
The first example script below makes use of the Clipboard. Copy the code and paste it into your AppleScript Editor (a.k.a. the Script Editor in systems prior to 10.6). From the Editor's File menu select Save As > File Format: application, and leave the Options unchecked. Once properly saved, the script must be run from the Dock or from the Script Menu.
When the insertion point is placed in the desired spot in a document (in Mail, or in whatever application), simply click on the script's docked icon, or select the script from the Script Menu. The predefined text will automatically be sent to the Clipboard and then pasted at the insertion point.
First example script (uses the Clipboard):
set the clipboard to "My Name" & return & "123 Main St." & return & "Anytown, Somestate 12345" & return
tell application "System Events"
keystroke tab using command down
keystroke "v" using command down
end tell
Naturally, the values "My Name", "123 Main St." etc. will need to be modified accordingly.
Another approach would be to bypass the Clipboard altogether. The second example types out the predefined text directly from the script itself, thus leaving the contents of the Clipboard intact. You might find
Full Key Codes to be a great help when modifying this one. As with the first example, the script needs to be saved as an application and must be run from the Dock or from the Script Menu.
Second example script (doesn't use the Clipboard):
tell application "System Events"
keystroke tab using command down
keystroke "My Name" & return
key code 18
key code 19
key code 20
keystroke " Main St"
key code 47
keystroke return
keystroke "Anytown, Somestate "
key code 18
key code 19
key code 20
key code 21
key code 23
keystroke return
end tell
Hope this helps.
