The 10.9.1 update improves the stability and compatibility of your Mac, and is recommended for all OS X Mavericks users.
This update includes the following fixes:
● Improved support for Gmail in OS X Mail, and fixes for users with custom Gmail settings.
● Improves the reliability of Smart Mailboxes and search in Mail
● Fixes an issue that prevented contact groups from working properly in Mail
● Resolves an issue that prevented VoiceOver from speaking sentences that contain emoji
● Updates Shared Links periodically when open in the Safari Sidebar
For detailed information about this update, please visit: http://support.apple.com/kb/HT6065
You can get the update by selecting Software Update from the Apple menu at the top left of your screen.