What is ActiveSync?

ActiveSync Infographic

ActiveSync, or to use its full name, Microsoft Exchange ActiveSync, is a proprietary email and collaboration protocol, first developed by Microsoft in 2002. ActiveSync uses an XML based format to synchronize not just email data, but all Microsoft Exchange data, including contacts, tasks, calendar and notes, with a Microsoft Exchange Server. This synchronization happens in real-time. Unlike other email protocols, ActiveSync is able to operate across HTTP and HTTPS connections, making it one of the most reliable protocols for roaming users, who may be operating across internet connections with usage restrictions in place.

Microsoft Exchange ActiveSync uses push technology to synchronize with a hosted exchange server. This means that emails, and updates to calendar, contacts, tasks and notes are sent to connected devices as they occur. There is no need to manually perform a synchronization.

Initially, ActiveSync was only available for users of Microsoft Outlook. However, now, many email clients as well as mobile devices can use ActiveSync. This means that a hosted exchange server can keep each device up to date, in real-time. However, at this time, only Microsoft Outlook offers full synchronization of all data, including collaboration events such as meeting invites and task assignment.

ActiveSync is implemented (to varying degrees) within Apple iOS, Google Android and BlackBerry OS. This allows smartphones and tablets to use a hosted exchange service to receive push delivery of email whenever connected to the internet. Any changes to email, tasks, contacts or calendar (on most devices) will be propagated to other connected devices in real time.

Microsoft Exchange ActiveSync is also supported natively by most Windows 8 applications, such as mail and calendar, with no additional need for Microsoft Outlook to be used as an email client.