The SMTP connection to server “p45-smtp.mail.me.com” failed.

Using Mail with macOS Catalina 10.15.6 (19G2021), Everything was working great until evening and I can't send outgoing emails anymore with my mail app using my mac.com email address? So frustrating.

Mail Connection Doctor gives

Status: Red

Account Name: iCloud

Account Type: SMTP

Details: Trying to log in to this SMTP account failed. Verify that the username and password are correct.

When I go to edit SMTP an iCloud SMTP doesn't even exist in my list. and in Server Settings when on my iCloud IMAP account it shows "iCloud (Offline)"

However I'm receiving emails fine to mail with mac.com account I just get this error when trying to send out emails with my mac.com email account. Please help! someone.