I re-applied according to the new recovery process through email. In response, I received the following mail.
Hello,
Thank you for your email. The signed message was successfully verified.
Please note that the email address cannot be restored to a different one other than the original used to register the account. In the situation where that email address was used to create a different account, you will need to change it on the second account as one email address cannot be linked with more than one acount.
Furthermore, we will need you to send us an email from that original email address where you wil also receive further instructions.
Best regards,
Bitcointalk account recovery team
But, I do not remember the original email ID with which my account was registered 5 years ago. Though, I have provided signed message from an address, that was used within one month of account registration.
What am I supposed to do?
It is likely that it is unclear you are the original owner of the account, based on your browser/ip/OS you are currently using, verses what you used when you registered your account.