Hi, Mail on El Capitan in behaving strangely for me. It says 'Checking for Email', counts up to around 150,000 new messages (presumably the sum total of emails on my Mac) at the same time downloading something (headers?) and eating 30%+ of CPU. It then repeats ad nauseum. I have 3 IMAP accounts and 1 Exchange account. Other than the above symptom the email app behaves normally. Any thoughts on how to fix this please?