Anyone else having this problem? I had a few accounts already in place when I updated to 10.9 and it was working fine but then I noticed that it was sending emails from the wrong accounts so I deleted them all from Mail with the intention of re-adding them one by one. Well, no dice. When I try to add a gmail account it goes through the whole process and I click "done" and then the account never shows up. Then I go into System Preferences and the accounts show up as inactive. I can go and enable each of the features (contacts, calendars, etc.) but as soon as I try to enable mail it will crash system preferences.