This is getting a little annoying. I was recently sent another certificate and received the exact same error condition.
http://screencast.com/t/flGrkDyOs
Let's review carefully the sequence of events here:
Part I
1) I followed instructions to follow Adagio on Twitter.
2) I successfully received a $5 promotion code
3) When I attempted to use this promotion, I received the error message
4) I then changed my Adagio account information to reflect the same email that my Twitter account is based on.
5) I then attempted again to checkout using the Twitter delivered promotional code and this failed to work
6) I post here to these forums and was told by "someone" that they ran through the checkout procedure with the code and it worked.
7) I tried again and it didn't work. Same error message about the email address (also take note that it is beyond 24 hours so that could possibly be why it no longer works even though the error message is incorrect at this point unless the promotion actually didn't expire despite the Twitter message saying it would.
Part II

I received an email indicating I had items in my cart but did not check out. I received a promotional code for $5 providing an incentive to complete the transaction.
9) I put two items in my cart, attempted to enter the promotional code but got the same error message regarding the email account.
10) I review the email again and it's addressed to the first email address I used when setting up my account, not the updated email address mentioned in step 4 above.
So here are my questions:
1) When the Twitter promotional code was sent, does anyone know which "email address" that code was tied to?
2) When generating a promotional code, how does the system know what my Twitter email address is?
3) After updating my email in my account profile, why am I still receiving email at the original address? This shouldn't be happening.
4) How can I get the discounts (2 @ $5 now) that were tendered to me?
I'm trying my best to be your customer but unfortunately, your system is not making it easy. I really wish someone would investigate the issue and get to the root cause as I should not have to follow up each order with a request in these forums to get a credit.