Apple has released macOS High Sierra 10.13.5 which primarily adds Messages in iCloud support, but it also includes some enterprise and security updates. You can download and install it from the Mac App Store now.
Messages in iCloud provide both more consistent chat (iMessages & SMS) syncing across your Apple-made devices and a way to free up space. You can delete a message on your Mac and it will now be removed on your iPhone, or set up a new iPad or Mac and access your entire conversation history.
You can read more about Messages in iCloud in our post How do I enable Messages in iCloud?
Apple's release notes:
"The macOS High Sierra 10.13.5 Update improves the stability, performance, and security of your Mac, and is recommended for all users.
This update adds support for Messages in iCloud, which lets you store messages with their attachments in iCloud and free up space on your Mac. To enable Messages in iCloud, go to Preferences in Messages, click Accounts, then select ”Enable Messages in iCloud.”
- Variables used in SCEP payloads now expand properly.
- Configuration profiles containing a Wi-Fi payload and SCEP payload install as expected when the KeyIsExtractable key of the SCEP payload is set to false."