I have just started (re)using Outlook with the 2007 release. So far loving it.
My response here would be Outlook 2007 based, so might defer slightly for previous versions.
I would think you would need to turn off auto send/receive. When you want to get new messages, you would have to manually do it by clicking the |send/receive| tab at the top.
Outlook > Menu > Tools > Send/Recieve > Send/Receive Settings > Click Define Send/Receive Groups (Crtl+Alt+S). Once here,
In the bottom half of the pop-up box make sure there is a check next to |Include this group in send/receive(f9).
Uncheck all boxes for 'All Accounts' group.
I just tried it. A delay send went out ok. And Outlook will only fetch when I manually click the |Send/Receive| tab at the top.
This should stop Outlook checking for emails
(PS: Any relation to Gerry Rafferty of 'Baker Street' fame? ;-) )