Understanding Exchange ActiveSync


Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

By default, when you install the Client Access server role on a computer that's running Microsoft Exchange Server 2010, you enable Microsoft Exchange ActiveSync. Exchange ActiveSync lets you synchronize a mobile phone with your Exchange 2010 mailbox.

Overview of Exchange ActiveSync

Exchange ActiveSync is a Microsoft Exchange synchronization protocol that's optimized to work together with high-latency and low-bandwidth networks. The protocol, based on HTTP and XML, lets mobile phones access an organization's information on a server that's running Microsoft Exchange. Exchange ActiveSync enables mobile phone users to access their e-mail, calendar, contacts, and tasks and to continue to be able to access this information while they're working offline.


Exchange ActiveSync can synchronize e-mail messages, calendar items, contacts, tasks, and notes.


Windows Phone 7 mobile phones only support a subset of all Exchange ActiveSync mailbox policy settings. For a complete list, see Windows Phone 7 Synchronization.

Features in Exchange ActiveSync

Exchange ActiveSync provides the following:

  • Support for HTML messages

  • Support for follow-up flags

  • Conversation grouping of e-mail messages

  • Ability to synchronize or not synchronize an entire conversation

  • Synchronization of SMS messages with a user's Exchange mailbox

  • Support for viewing of message reply status

  • Support for fast message retrieval

  • Meeting attendee information

  • Enhanced Exchange Search

  • PIN reset

  • Enhanced device security through password policies

  • Autodiscover for over-the-air provisioning

  • Support for setting auto-replies when users are away, on vacation, or out of the office

  • Support for tasks synchronization

  • Direct Push

  • Support for availability information for contacts

Managing Exchange ActiveSync

By default, Exchange ActiveSync is enabled. All users who have an Exchange mailbox can synchronize their mobile phone with the Microsoft Exchange server.

You can perform the following Exchange ActiveSync tasks:

  • Enable and disable Exchange ActiveSync for users

  • Set policies such as minimum password length, device locking, and maximum failed password attempts

  • Initiate a remote wipe to clear all data from a lost or stolen mobile phone

  • Run a variety of reports for viewing or exporting into a reporting solution

Security in Exchange ActiveSync

You can configure Exchange ActiveSync to use Secure Sockets Layer (SSL) encryption for communications between the Exchange server and the mobile phone client. Certificate-based authentication works with a self-signed certificate, a certificate from an existing public key infrastructure, or a third-party commercial certificate. You can use certificate-based authentication together with other security features, such as local device wipe and a device password, to turn the mobile phone into a smartcard. The private key and certificate for client authentication are stored in memory on the mobile phone. If an unauthorized user tries to bypass the mobile phone password, all user data is purged. This includes the certificate and private key. For more security, you can deploy RSA SecurID two-factor authentication on the Exchange server.

Device Security Features in Exchange ActiveSync

In addition to the ability to configure security options for communications between the Exchange server and your mobile phones, Exchange ActiveSync offers the following features to enhance the security of mobile phones:

  • Remote wipe   If a mobile phone is lost, stolen, or otherwise compromised, you can issue a remote wipe command from the Exchange Server computer or from any Web browser by using Outlook Web App. This command erases all data from the mobile phone.

  • Device password policies   Exchange ActiveSync lets you configure several options for device passwords. These options include the following:

    • Minimum password length (characters)   This option specifies the length of the password for the mobile phone. The default length is 4 characters, but as many as 18 can be included.

    • Minimum number of character sets   Use this text box to specify the complexity of the alphanumeric password and force users to use a number of different sets of characters from among the following: lowercase letters, uppercase letters, symbols and numbers.

    • Require alphanumeric password   This option determines password strength. You can enforce the usage of a character or symbol in the password in addition to numbers.

    • Inactivity time (seconds)   This option determines how long the mobile phone must be inactive before the user is prompted for a password to unlock the mobile phone.

    • Enforce password history   Select this check box to force the mobile phone to prevent the user from reusing their previous passwords. The number that you set determines the number of past passwords that the user won't be allowed to reuse.

    • Enable password recovery   Select this check box to enable password recovery for the mobile phone. Users can use Outlook Web App to look up their recovery password and unlock their mobile phone. Administrators can use the EMC to look up a user's recovery password.

    • Wipe device after failed (attempts)   This option lets you specify whether you want the phone's memory to be wiped after multiple failed password attempts.

  • Device Encryption Policies   There are a number of mobile phone or device encryption policies that you can enforce for a group of users. These policies include the following:

    • Require encryption on device   Select this check box to require encryption on the mobile phone. This increases security by encrypting all information on the mobile phone.

    • Require encryption on storage cards   Select this check box to require encryption on the mobile phone’s removable storage card. This increases security by encrypting all information on the storage cards for the mobile phone.

Windows Phone 7 Synchronization

If you have Windows Phone 7 mobile phones in your organization, these phones will experience synchronization problems if certain Exchange ActiveSync mailbox policy properties are configured. To allow Windows Phone 7 mobile phones to synchronize with an Exchange mailbox, either set the AllowNonProvisionableDevices property to true or only configure the following Exchange ActiveSync mailbox policy properties:

  • PasswordRequired

  • MinPasswordLength

  • IdleTimeoutFrequencyValue

  • DeviceWipeThreshold

  • AllowSimplePassword

  • PasswordExpiration

  • PasswordHistory

  • DisableRemovableStorage

  • DisableIrDA

  • DisableDesktopSync

  • BlockRemoteDesktop

  • BlockInternetSharing

 © 2010 Microsoft Corporation. All rights reserved.