Announcing the deprecation of Exchange Client Extensions

You might ask: What are Exchange Client Extensions (ECEs) and why does this deprecation matter to me? For most Outlook users, this announcement will not concern you. However, if you are a developer that uses Exchange Client Extension interfaces to build a solution in Outlook, then this deprecation is significant because you will have to redesign your solution for Microsoft Outlook 2010.

Exchange Client Extensions (ECEs) represent an extensibility feature introduced with the Microsoft Exchange client in 1995. The Exchange client was a 16-bit mail application running against the earliest versions of Exchange Server. ECEs must be written in native code, typically using C++ and relying heavily on the Messaging API (MAPI). When Outlook replaced the Exchange client, ECEs were used to extend Outlook 97-98 until COM Add-ins replaced ECEs in Outlook 2000 as the primary extensibility technology for Outlook.

ECEs will continue to operate as expected in Outlook 2007 and earlier. However, ECEs will not load in Outlook 2010. Outlook 2010 has converted its own ECEs such as Delegate Access, Deleted Items Recovery, Exchange Extensions commands, and Exchange Extensions property pages to native Outlook code. To redesign your solution, you should consider the following options:

  • Rewrite your ECE as a COM Add-in using native or managed code. Unlike ECEs, an add-in represents a strategic extensibility technology that is fully supported in Outlook 2010. Using an Outlook add-in, you can build Outlook form regions and extend the Office Fluent User Interface. For additional information, please visit the Outlook Developer Portal on MSDN.
  • Rewrite your ECE as a Windows service application using native code and MAPI. If you are writing a Windows service application, you must use MAPI to access Outlook items rather than the Outlook object model.

If you are a developer, we’d like to hear your feedback about this announcement. Let us know if you plan to redesign an ECE and your concerns about parity between ECE interfaces and the Outlook object model.

Randy Byrne

Outlook Program Manager

Office Blogs Comments

Comments: (6) Collapse

  • This is not good news for us. We tried to use a COM Add-in and could not offer the same functionality with the available interfaces. I suspect you will be leaving a number of vendors in the same position as us. Chris Rowen

    Director Advanced Development - Messaging

    EMC

  • Chris, I look forward to working with EMC to ensure interface parity with ECEs and Outlook 2010. Thanks for your feedback. Randy Byrne Outlook Program Manager

  • Hi Randy,

    I have a request for the outlook team. How many e-mails are sent in to world where the sender forgot to send the attachment and sends a follow on message with the attachment and a "whoops...forgot attachment!" message body! I've lost count of the amount of times I've done it and others. We are not alone :) A simple solution: When sending an e-mail, scan the body content for the word attachment(s) and check if an attachment is 'attached'. In the case of no attachment being attached, show a simple dialogue box with the message 'your mail mentions an attachment but you have no attachment on this e-mail. Do you wish to attach one" yes/no (or something to get the message across). Think of the millions of users who would save embarrassing follow on mails and the amount on duplicate mails that would be eliminated. Daniel (dan.mcsweeney@gmail.com) in case the people from the nobel prize wanna talk :)

  • Hey Dan,

    check out the Forgotten Attachment Detector! www.officelabs.com/.../default.aspx

  • From what I can tell, in Outlook 2010 the registry key to load custom rule actions no longer has any effect.

    So I believe they also disabled COM addins for Custom Rule Actions in 2010.

    Has anyone been able to load a custom rule action dll in 2010?

  • Hello,

    I am a newbie to MS technologies. I am trying to convert an ECE (which works in Outlook 2007 and below) to a COM add-in so that it will work in Outlook 2010.

    Which is the best forum to ask questions about this conversion? Please let me know.

    Thanks

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