fine, i have added my hotmail account via Outlook connector, sent 30MB bmp file. It have stuck in outgoing emails folder however i had not problems deleting it when in offline mode.

Try to do this: click on send/receive drop down list - expand "send/receive settings" and choose show progress.
If the email is still about to be sent (i am not sure how does this work if you are in offline mode) just cancel this task. It worked for me as well and it deleted the large email from outgoing emails folder.
In case you will not have this task shown there, try to go to online mode, wait until it start sending it (or send it manually via send/receive) and try to do the above.

Let me know if that helped.

Kind regards,
Wries