Apple has released OS X 10.10.5:
The OS X Yosemite 10.10.5 update improves the stability, compatibility, and security of your Mac, and is recommended for all users. This update:
Improves compatibility with certain email servers when using Mail
Fixes an issue in Photos that prevented importing videos from GoPro cameras
Fixes an issue in QuickTime Player that prevented playback of Windows Media files
Mac owners can update to OS X 10.10.5 and iTunes 12.2.2 (connected to OS X 10.10.5) by clicking the updates tab in the App Store app.