Like Spark for iOS, Spark for Mac includes a Smart Inbox feature, which intelligently organizes email into different categories (Personal, Notification, and Newsletters), to make sure important messages are always highlighted first.
Learning capabilities allow Spark to be told when an email is important, and the next time a similar message is received, it'll send a notification. Spark's Smart Notifications are designed to make sure you only get a notification when you get a message worth being alerted about.
Spark for Mac includes natural language search, so it responds to commands like "Find all my emails with PDFs," or "Find the email from Eric last Tuesday," and there are deep customization tools for personalizing Spark to meet your needs.
Other Spark features include Quick Replies, Touch Bar support, snooze capabilities, and cross-device syncing.
Spark for Mac is available from the Mac App Store starting today. Like Spark for iOS, Spark for Mac is a free app. [Direct Link]
Update: Readdle says the launch has been delayed, as Apple's approval of Spark for Mac is still pending.
Update 2: Spark for Mac is now available for download from the Mac App Store.