Mac Mail Keeps Downloading

Not sure what happened but it seems after the 10.11.1 update my mac mail went crazy. Every time I open mail, it starts to download over 18,000 messages. It does the over and over. My ...library/mail folder is up 17.25 GB. That seems a bit large, not to mention during the message downloads, mail is hogging over 70% of my CPU resources. Any ideas...I have 2 AOL accounts and 2 Gmail accounts.

Thanks.