There are a couple more things you could try to get closer to debugging the situation:

1) Check with your mail provider if there is any filtering which might prevent emails from mtgox arriving etc.
If not - ask mtgox support to send you a test email from the same system which sends out password reminders so you can test that you're getting email from them ok.


2) ask mtgox if you can supply them with transaction ids from your bitcoin wallet from when you deposited BTC to demonstrate your claim.

Perhaps a long shot - but something to try.

If they really do archive inactive accounts which have a balance, without a way to lookup via email address - that's not very good.   Put in a 'bug report' for them to fix that.. and wait??