Today, Apple released the first update to OS X Mavericks, OS X 10.9.1. The new version, available for download on the Mac App Store through Software Update, brings improvements for Mail and Gmail compatibility and makes Smart Mailboxes and message search more reliable. Version 10.9.1 is the first public update to Mavericks, originally launched on October 22.
The built-in Mail app was heavily criticized after the launch of the free Mavericks update as changes made by Apple under the hood impacted the performance of the app when used with Gmail or with large mailboxes containing thousands of messages. In November, Apple released an initial standalone Mail update to improve the “general compatibility” with Gmail.
OS X 10.9.1 contains other improvements that Apple will detail in a document available here.