Problem Mail (10.8.5) and lost 'out' emails

Hi,

Macbook air 11in, running Mountain Lion (10.8.5).

Mail connects to exchange.

Last night the AD (exchange) account got locked out without my knowledge.

I continued to create emails and send them. I heard the 'wosh' sound so assumed everything was fine.

Subsequently I realised that I wasn't receiving emails and discovered that the AD account was locked out (it auto resets after a time period).

However, any emails that I composed adn 'sent' while the account was locked out have disappeared. They are not present in the drafts or sent items.

I don't see an 'outbox' but if I search within mail I see the 'outbox' and I can open it, but it is empty.

Once the AD account was unlocked, I can send mail normally again and the emails appear in sent items. However, the emails created and sent while the account was locked out have disappeared and I cannot find them anywhere.

I have treid rebuilding the 'sent' and 'drafts' folder in mail but this has not recoveredthe emails.

Is this a bug in Mail?

Any suggestions?

Thanks.