Hello, What stops you from doing that? The more info and screenshots you gave us, the better.

I don't know I just added a new email but it doesn't show up on thunderbird email popup so i can send or reccive messages

Can you show me a screenshot of what you did (while removing the private info). Was it via the account hub or via the wizard? At what stage it gave error?

I used new account old hub no error message it just does not show up on thunderbird popup when i turn on thunderbird to send or send emails It is not listed with my other accounts

any new word on why my email account sonnylee14@aol.com does not show up thunderbird popup. I cannot send or receive emails until it is there

I am locking this duplicate of https://support.mozilla.org/en-US/questions/1531395.

Please post instead to https://support.mozilla.org/en-US/questions/1531395

Note, what you refer to as a pop up is what we call a dialog.