How do I stop a message being sent after it has already starting

[Natd]

I created a message and attached several photos to it, and then pressed send.
it has now been in the process of sending for 2 days, and I can't delete it
or stop it.

 

[VanguardLH]

I created a message and attached several photos to it, and then pressed send.
it has now been in the process of sending for 2 days, and I can't delete it
or stop it.

Your e-mail exceeds the maximum size for a message as established by the
quotas at your e-mail provider.

Delete an item stuck in the Outbox folder:
- Load Outlook.
- Put Outlook in offline mode (File -> Work Offline, enable).
- Optional - If Outlook touches the stuck item, you can't delete it.
If you touched the item:
o Exit Outlook.
o Load Outlook in its safe mode ("outlook.exe /safe"). This ensures:
+ No plug-ins get loaded that might touch the item.
+ Loading Outlook in offline mode means it won't touch the stuck
item.
- Delete the stuck item in the Outbox folder.
- Put Outlook in online mode (File -> Work Offline: disable).
- If you restarted Outlook in its safe mode, exit and restart Outlook
for normal operation.