Use MailTags to escape the constraints of folders and organize your messages by keywords, projects and other metadata. Base your order on what a message is, rather than where it is.

Build Flexible Organization:
Use MailTags to escape the constraints of folders and organize your messages by keywords, projects, importance, color, due dates and more. Quickly tag your messages using MailTags fluid tagging window.

Search Tags & Find Mail:
Use MailTags' powerful search and smart mailbox integration to quickly locate your messages. MailTags data is concisely displayed inline with your messages and dynamically color messages based on importance, project, or upcoming date.

Create Email Workflow:
Create rules to automatically assign tags to your incoming messages. Add tags to your messages as you compose. Combine Mail Act-On, and other applications to fully integrate your email into your workflow.

Requirements:
OS X 10.11.6+
64-bit Intel

Also available is:
Intel version 4.2.9 for OS X 10.9- 10.10