Sunday, 9 January 2011

Additional Exchange configuration for Outlook 2011 for Mac

Enable Outlook 2011 for Mac to send larger attachments

Outlook 2011 for mac connects to exchange server 2007 using EWS (Exchange web services), and by default connecting to exchange server is very simple; however if your organisation allows for message attachments greater than 13MB you will need additional configuration on the server side. One of the more common error messages is Error 18500

I noticed a few articles directing people to edit the OWA virtual directory within IIS; however this is not necessary unless you require larger attachments to be sent using OWA. I did not have a requirement to send large files using OWA; therefore I only configured the settings outline below.


Outlook 2011 was not released at the time of the article below; however both technologies using EWS for connectivity to Exchange 2007.

Microsoft Entourage 2008 for Mac, Web Services Edition

1. This version of Entourage for Mac uses the Microsoft Exchange Server 2007 Web services provider to send mail.

To allow for larger attachments that you must change the MaxRequestLength in the web.config file.

By default, the web.config file is located in the EWS Virtual directory Microsoft\Exchange Server\ClientAccess\exchweb\EWS will have the following entry, by default, the max request size is approximately 13MB

httpruntime maxrequestlength="13280"

Change the item to where X is the desired value in KBs. for example, X will be approximately 50000 (50MB). 

You must restart IIS services after making this configuration change.