Evolution outgoing mail issue

Help is needed with Evolution, where I got blocked outgoing mail. This causes the situation from which I am unable to send any mail. Outbox folder shows 1 unsent message, however this is not visible anywhere = blocking mail. Any other mail I compose stucks behind the blocking one. All composed mails I can see and delete, except the blocking one. Expunge has not worked, and recently I reinstalled Evolution, but the situation remains the same.... any suggestions guys ???thank you