Have them only open Outlook between 2 and 6 or have them work offline until 2 PM.
"There are seldom technological solutions to behavioral problems." - Internet Guru

Signature
Milly Staples [MVP - Outlook]
Post all replies to the group to keep the discussion intact. All
unsolicited mail sent to my personal account will be deleted without
reading.
After furious head scratching, stephenson.chris@gmail.com asked:
| Running Exchange 2003 with sp2 and SBS 2003 with sb1 looking at a way
| to delay inbound email.
[quoted text clipped - 10 lines]
| Cheers,
| Chris