"The OS X El Capitan 10.11.1 update improves the stability, compatibility, and security of your Mac, and is recommended for all users.About the OS X El Capitan v10.11.1 Update - Apple Support
- Improves installer reliability when upgrading to OS X El Capitan.
- Improves compatibility with Microsoft Office 2016.
- Fixes an issue where outgoing server information may be missing from Mail.
- Resolves an issue that prevented display of messages and mailboxes in Mail.
- Resolves an issue that prevents certain Audio Unit plug-ins from functioning properly.
- Improves VoiceOver reliability.
- Adds over 150 new emoji characters with full Unicode 7.0 and 8.0 support.
- Resolves an issue that caused JPEG images to appear as a gray or green box in Preview."
Friday, October 23, 2015
About the OS X El Capitan v10.11.1 Update - Apple Support
Emphasis below is mine