One substantial issue that has affected users after upgrading to OS X El Capitan is that Mail messages might be missing. In some cases it may be a few messages, while in other cases entire accounts have been emptied with no messages available. Sometimes this type of problem can be fixed by adjusting account settings to re-establish contact with your account servers, after which re-syncing will download your messages again; however, this does not always happen.
In this instance Apple has recognized problems with Mail in the initial release of El Capitan, and has issued a fix in the latest OS X 10.11.1 update. Nevertheless, those who have installed it may still have their messages missing.
Use Time Machine after updating
Apple’s Mail e-mail client is one of a few programs that will allow you to access backups directly in the program itself. This means that you should be able to access and restore missing messages relatively easily:
- Open Mail.
- Invoke Time Machine.
- Navigate to the most recent backup that has your messages.
- Select all by pressing Command-A (or use Shift or Command to create a custom selection).
- Click the Restore button to copy your messages back to Mail.
Restore and re-update
If you have recently installed OS X 10.11.0 and have a backup, then you can alternatively restore your Mac and then try reinstalling El Capitan, upgrading directly to OS X 10.11.1 (the one that contains the fixes to Mail), as opposed to trying your hand in the potentially faulty OS X 10.11.0 update:
- Reboot your Mac to Recovery mode (hold Command-R at startup).
- Attach your Time Machine backup drive to your Mac.
- Choose the tool for restoring your Mac from Time Machine.
- Follow the on-screen instructions for restoring the most recent backup.
- Ensure your Mail accounts are accessible and your messages exist.
- Access the App Store and re-download El Capitan.
Since Apple has updated the App Store distribution of El Capitan to reflect the latest version, this will ensure you go directly to the latest as opposed to upgrading and then needing to update. After this is done, check your messages to ensure they are present.