After upgrading to Mountain Lion:
- Your Exchange email account may not connect in Mail.
- You may receive an error message when attempting to send or receive messages.
- Your settings appear to change each time you quit and open Mail.
Mountain Lion includes full support for Autodiscovery. As part of this feature, each time Mail is opened, it asks your Exchange server what settings your mail account should use when connecting to the server. As part of Autodiscovery, Mail will change your settings to reflect what the Exchange server offers. Prior to OS X v10.8, this could result in your settings unexpectedly changing.
In OS X v10.8.1 and later, you can use the below steps to disable Autodiscovery and instead use the settings that your Exchange admin directs you to use for your Internal and External Mail Server.
To disable Autodiscovery in OS X Mountain Lion
- Update to OS X v10.8.1 or later.
- Open Mail, then choose Mail > Preferences.
- Uncheck (deselect) the "Use Autodiscovery Service" checkbox above the Internal and External server settings. When Autodiscovery is unchecked, the Internal and External mail server addresses can be edited.
If you have issues connecting to the Exchange server or don't know what server addresses to use, contact your Exchange administrator or IT administrator.