How do I ask existing users for backup email for password recovery?

1. How do I retrieve an old email account?
2. How to get back into my Facebook account without password or email?
3. How do I find my backup emails in Gmail?

How do I retrieve an old email account?

Recover your account

Go to the account recovery page. Answer the questions to the best of your ability. Tip: There's no limit to the number of times you can attempt to recover your account. To recover your Google Account or Gmail, follow the steps on the account recovery page.

How to get back into my Facebook account without password or email?

You may be able to get back into your Facebook account by using an alternate email or mobile phone number listed on your account. Using a computer or mobile phone that you have previously used to log into your Facebook account, go to facebook.com/login/identify and follow the instructions.

How do I find my backup emails in Gmail?

Go to your Google Account. On the left navigation panel, click Personal info. Recovery email.