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Plan for Exchange Online application compatibility


Topic Last Modified: 2014-04-30

Summary: Describes conditions that apply to hosted applications and methods of connecting them to Exchange Online, including MAPI, SMTP relay, and others.

Administrators can connect many kinds of on-premises and hosted applications to Exchange Online, including custom line-of-business applications and software from third-party vendors.

The following conditions apply to hosted applications:

  • The application vendor must provide support for the application and perform all related application compatibility testing.

  • Custom applications cannot be hosted in a Microsoft datacenter unless they are hosted on the Microsoft Azure platform.

  • Exchange Online does not host custom code or third-party applications, including DLL files, custom code packaged in transport agents, or modifications to files on servers in the datacenter.

The following sections describe the methods available for connecting applications to Exchange Online and identify some Exchange Server application programming interfaces (APIs) that are unavailable in Exchange Online.

Exchange Web Services (EWS) is the preferred development API for Exchange Server and Exchange Online. Using EWS or the EWS Managed API, administrators can access data stored with Exchange Online from applications that are running on-premises, in Azure, or in other hosted services. EWS can perform specialized actions, such as querying the contents of a mailbox, posting a calendar event, creating a task, or triggering a specific action based on the content of an email message. For information about how to use Exchange Web Services with Exchange Online, see the technical articles at the Developer Center for Microsoft Exchange Online.

Exchange Online can be used as an SMTP delivery service to relay email messages sent from fax gateways, network appliances, and custom applications. For example, if a line-of-business application sends email alerts to users, it can be configured to use Exchange Online as the mail delivery system. The application or service must authenticate to a valid, licensed Exchange Online mailbox and connect over TCP port 587 using TLS.

For information about how to configure SMTP relay with Exchange Online, see the Microsoft Support article How to set up an SMTP relay in Office 365.

Exchange Online supports Outlook Web App Web Parts, which provide access to content in Outlook Web App directly from a URL. Web Parts are usually embedded in a custom application or a web-based portal, such as SharePoint Online or SharePoint Server.

For more information, see the TechNet article Using Outlook Web App Web Parts.

Most Outlook add-ins will work with Exchange Online. However, Microsoft does not provide support or troubleshooting help for Outlook add-ins. Customers must contact the vendor that created the add-in for assistance.

Applications that use the Outlook MAPI library to connect to Exchange Online usually work, but those that use the Exchange Server MAPI library will not work. See the the following Exchange Server MAPI/CDO section for more details.

If an application requires Outlook to be installed in order to function, it probably uses the Outlook MAPI library.

Some third-party applications use Exchange Server MAPI client and Collaboration Data Objects (MAPI/CDO) for server-to-server communication with Exchange. These applications need to be installed within the same local network as Exchange and will not connect over the Internet to Exchange Online.

Lync Online can be configured for domain federation with an on-premise Microsoft Office Communications Server 2007, Office Communications Server 2007 R2, or Lync Server 2010 as long as Lync Online and the on-premise system are using different SIP domains.

On-premises Lync Server 2010 can interoperate with Exchange Online in two ways:

  • IM and presence interoperability in Outlook Web App

  • Voicemail interoperability

The Exchange WebDAV API was removed from Exchange Server 2010 and is not available for use with Exchange Online.

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