HT1277 Mail keeps asking login credentials for a removed Exchange account

Question

Removing an Exchange account does not seem to be enough to stop Mail from attempting to connect the Exchange server. Every now and then Mail pops up a dialog prompting for login credentials for an Exchange account I have previously removed. This seems to happen very consistently every time I visit the Accounts tab in Settings.
My question is: How do I get rid of whatever little data there is left of the removed Exchange account?

Answer 1

Basically, the fix is to put all your mail passwords in a separate, always-unlocked keychain.
Here is how to do this:
1) Open keychain access, go to File -> New Keychain. I named mine Mail. Save it in your keychains folder (default), and give it a password.
2) Right click the new keychain and select "Change Settings for Keychain". Here, uncheck the "Lock after" and the "Lock when sleeping". The latter can be left on if you don't mind re-typing your password every time your computer goes to sleep (can also be more secure if you don't lock your whole machine when sleeping).
3) Here is the tricky part: you need to find all your mail keys and drag them into the new keychain. Do a search for your mail host or your login username and you might see a list of keys. It will be flagged as an "Internet password", not web form, and when you click on it it should read "imap://your.web.host.tld/" or pop if you use that, and "smtp://your.web.host.tld/" for your outgoing mail. Just drag them all into your Mail keychain, type in your password and click Accept. The keys will stay on the search screen, but clicking on the Mail keychain will confirm that they are in fact moved.
4) Now lock your primary keychain (the one in bold) and run a test by checking your mail. If no dialog pops up asking for your keychain password then it was a success!