Mail keeps "losing" passwords to all email accounts OSX10.8.5

In the last few days, my Mail has been acting bizarrely. None of the passwords are in the Mail Preferences / Account settings, and it also seems to drop the Outgoing server info. Regardless of how many times I re-enter those and save, once I'm out of the Mail Preferences / Account settings, they apparently disappear again.

I found a number of threads that seem to relate to Yahoo and AOL accounts, but I do not have any of these, instead: hosted domain email, gmail and an office.365 Exchange server. As I run my consulting business remotely from most of my clients, consistently working email is essential. This is really making work impossible! I've already ditched Outlook due to consistently having horrible issues, to the point of it erasing my identities after an automatic update (putting me out of business for several days as we had to rebuild my entire email).

Does anyone have a working solution for this mail losing passwords issue?