The OS X Yosemite v10.10.1 Update improves the stability, compatibility, and security of your Mac. This update:
Improves Wi-Fi reliability Improves reliability when connecting to a Microsoft Exchange server Resolves an issue that may prevent Mail from sending messages through certain email service providers Addresses an issue prevents connecting to remote computers using Back to My Mac Resolves an issue where sharing services, Notification Center widgets and Actions may not be available Addresses an issue that could cause Notiication Center settings to not be retained after a restart Addresses an issue that might prevent the Mac App Store from displaying certain updates Addresses an issue that could prevent some Mac mini computers from waking from sleep Resolves an issue that might prevent Time Machine from displaying older backups Addresses an issue that might prevent entering text in Japanese