Deleted emails immediately reappear in Inbox

As soon as I delete unwanted emails, whether read or not, they immediately reappear in my Inbox as “Read” so I have to delete them again and again and again.

Also, new emails download multiple times, so my Inbox may have 2, 4, 5, copies of the same email. When I attempt to delete the extra copies, they reappear in my Inbox as well.

This is so frustrating and time-consuming.

Any help greatly appreciated!