Thanks Richard, I had a play around and reverted to this but I have a couple of issues.

;$ReturnCode = KeyExist("HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\Default Outlook Profile")
$ReturnCode = KeyExist("HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\Outlook")
If $ReturnCode
SHELL "sc config messenger start= demand"
SHELL "NET START Messenger"
SHELL "sc config messenger start= disabled"
$RC = SendMessage("MATAURA", "Test")
ELSE
?"Do nothing"

Endif

It seems to work (sending test message to itself at the moment) but since my PC is Vista, it doesn't have the messenger service so it's becoming difficult to test.

Any ideas?