Well I probably should have waited before upgrading, it seems this happens every single time there is an update. My gmail account that is set up as an IMAP account with Apple Mail isn't pulling in the emails that are coming into that account. I get them on my iPhone. But not on Apple Mail. Connection doctor says to check the user name and password. I went on there and they're right. The only odd thing I see in Mail>Preferences>Accounts is that on the outgoing mail server, it says offline. When I go into it, there is no password there. I type in the password. Close out of it. Then it reverts back to no password... I doubt there is a fix yet, but posting in hopes that someone else has figured out a way to make it work.