NT4 Exch 5.5 – how to recall sent mail ?

We have NT 4.0 Domain running Exchange 5.5 server, users have Office 2000 & few XP (Outlook 2000/XP) –
1. How do I recall a sent email using Exchange Server 5.5 & Outlook 2000 Client ?
2. Can I have “highlighter” option when writing emails in Outlook 2000 Client… like we have in Word 2000 to highlight (color texts) in yellow.

Is this both possible only in Outlook XP – if yes, how ?

Akash