Your e-mails are suing you?

Firefox is a web browser. It displays what the websites tell it to. This is an e-mail provider issue.

Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

in the past I have signed in Firefox using my other e mail accounts. For recovery secondary mails, when I enter the other mails that I had used to sign in, it tells me that emails are used by other users. I want to fix the problem. I have deleted old profiles and cookies but that does not help.

I called for more help.