[8] The Exchange Online version, which can be bought either independently or through Office 365 licensing program, is hosted on Microsoft servers on the World Wide Web.

[8] Outlook Web Access was created in 1995 by Microsoft Program Manager Thom McCann on the Exchange Server team.

The first component to allow client-side scripts to issue HTTP requests (XMLHTTP) was originally written by the Outlook Web Access team.

With the 2015 update, Microsoft introduced the ability to pin, sweep and archive messages, and undo the last action, as well as richer image editing features.

With the update, Microsoft added a weather forecast directly in the Calendar, as well as icons (or "charms") as visual cues for an event.

Microsoft was slowly rolling out a preview of Tasks to its consumer-based Outlook.com service that in May 2015, was announced to be moving to the Office 365 infrastructure.

A feature added was the ability to set due days and sort and filter the tasks according to those criteria.

The app provides the user with fields such as subject, start and end dates, percent complete, priority, and how much work was put into each task.

[17] Outlook on the web has had two interfaces available: one with a complete feature set (known as Premium) and one with reduced functionality (known as Light or sometimes Lite).

[20] Exchange 2010 supports a wider range of web browsers: Internet Explorer 7 or later, Firefox 3.01 or later, Chrome, or Safari 3.1 or later.

In Exchange Server 2007, the Light interface supported searching mail items; managing contacts and the calendar was also improved.