How to cancel an outgoing 'send' in Outbox (30mb)?

[Ted]

A message in my Outbox is too big to send (30mb) and needs to be canceled.
Efforts to 'delete' the message get the message, "Outlook has already begun
to transmit ...". Thanks for any suggestions.

 

[Gordon]

A message in my Outbox is too big to send (30mb) and needs to be canceled.
Efforts to 'delete' the message get the message, "Outlook has already
begun
to transmit ...". Thanks for any suggestions.

Click File and check Work Offline. Close and then restart Outlook. Delete
the message. Click File and uncheck Work Offline.

If that doesn't work, try this:
http://www.outlook-tips.net/howto/stuck_message.htm