Emails are not downloading to my Macbook/quota problem? why

Either after receiving this "message" : " I got a bunch of notifications saying that my icloud is hacked and there is a trojan virus on my computer." and then I think, cannot correlate this directly, when I installed Sequoia on a Mac mini and playing around with Hiding my email, etc and iCloud mail. I have many medical and important contacts that usuallycommunicate via those email accounts not downloading, but they go out, since I have sent from another of my emails, but they don't arrive. I may be missing messages for medical appointments and much more that I don't know. But where are those emails? Who is receiving them? How can I reinstate them. Some of them I have seen on a TRASH folder and sometoimes Receive a message that "the account has surpassed a "quota". How can this be fixed? I do not want to delete the account because I loose all.