Todoist for Outlook

Todoist for Outlook is an Outlook add-in which lets you set an email as a task with one click, so you'll always remember to follow up. It has advanced task management features let you organize tasks into projects, create nested-tasks, set priorities and deadlines, and use color-coding to manage your inbox. It automatically synchronizes your tasks across all your devices - smartphones, tablets, laptops, desktops - so you always have up-to-date access.

Requirements:

Microsoft Outlook