Bugs in Outlook (and you yourself) can cause messages to be sent
unfinished, without attachments, or with tone and content you regret
immediate

Tools Rules and Alerts
New Rule
Start from a blank rule.
Check messages after sending. Next
Don't select anything (apply to all messages) Next (accept the prompt)
Defer delivery to a number of minutes. 1 min is the minimum - should
be enough to catch the accidental sends and the ones you immediately
regret :-) Next
Don't add any expections. Next
Name the rule something like "Delay send for 1 minute". Tick turn on
rule.
Finish.

Relax for a minute after sending any message - even urgent ones.
Remember - you used to have to wait for a courier even for the most
urgent messages :-)

D