Mailspring is free forever for Mac, Windows, and Linux!
With your Mailspring ID, you can use Pro features like Snooze, Send Later, Send Reminders and Read Receipts a few times a month for free.
To unlock unlimited use of Pro features, you’ll need to purchase a subscription to Mailspring Pro within the app. Mailspring Pro costs $8/mo (or $85/yr if you prefer), and helps support the development of Mailspring. Learn more here: About Mailspring Pro Subscriptions