Email error (but not in email list)

Hello, I have noticed, that I got alot of email errors on my tiers and when I want to fix the problem and remove the email that shows an error, the email is not in the list? Is this a bug? because it shows me always error for some specific emails, but I cant find them. Regards

same lots of error in every project now and that red mark poup in project every 5 minutes

any fixes for that?