I have a 12 word passphrase and password from blockchain.info. Trouble is that I can't remember the email I used. Is there a way to retrieve the email with these two pieces of information?
If you have your 12 words phrase from blockchain.info you can just restore your wallet, then you will use a new email and new password.
To restore your blockchain.info wallet:
1 - Go to: https://login.blockchain.com/#/login
2 - Click on Need some help?
3 - Click on Recover Funds
4 - Use your 12 word phrase, lowercase, with spaces between each word.
There are two type of 12 word mnemonics from blockchain.info.
They use different word sets and have different meanings depending when they were created.
Pre 2015/2016 12 word seeds cointained your password to log in and were combined from a 50k plus word list. It was called the Legacy mnemonic.
Post 2015/2016 12 word list were combined from a 2048 word list and could be used to restore your public and private keys. These mnemonics are called HD
The blockchain uses separate links to check the validity depending if you have have the Legacy or HD.
If you enter the list in the HD link and it says word not recognised it is most probably Legacy.
If you get checksum error only then most probably one of your words is misstyped, missspelled, wrong or missing. In that case it is possible to calculated the correct word but it is not an out of the box solution.