In case anyone has ever had a problem getting Mail.app to trust certificates for secure connections, here’s the lowdown:
- Try and make your secure connection like you normally would. This could be either an IMAP connection or SMTP over TLS.
- When you get the prompt (the one you’re trying to get rid of), click the Show Certificate button.
- Now that you’re looking at the cert info, you’ll see an icon representing the cert itself. Option-drag that icon onto your desktop.
- Double-click that icon.
- Keychain will open and you will be prompted to import the cert. Pull down the X509Anchors option and say ok. Enter your credentials to authorize the addition.
There are other ways to do this involving chickens, the command line, and Gregorian chants, but believe me — this is the easiest way.