I encountered an issue with a client today where there were emails missing from their inbox in Entourage, yet when the user viewed their inbox in either Outlook Web Access, or used Citrix to view their inbox in Outlook, all the missing emails were there as clear as day.

We tried rebuilding their Entourage database, tried deleting their Exchange account and then rebuilding their Entourage database, tried moving the messages around from the Inbox into a subfolder, tried marking them as read/unread/flagged/unflagged… Nothing seemed to work.

In the end, it turns out that Entourage, when talking to Exchange 2007 on Windows Server 2008, has issues where it can’t see any emails that have a + character in their Subject. Yes, you did read that correctly, it flips out when trying to retrieve an email with a plus character in the Subject line. Weird.

Turns out it’s a security feature “… this is by design.” in Exchange 2007 to protect against double escaped sequences. Check out the blog posting at the following URL for some more in-depth technical information and how to alleviate the issue.

Inside Entourage by Amir : E-mail Download Issue in Entourage With Exchange 2007 on Windows 2008.

From the blog post, here are the two ways to fix it – one with a single command in CMD, the other by editing a text configuration file. How unixy!

Quick & Easy Way
You will need to run this command on all of your Exchange 2007 CAS and Mailbox Servers as IIS is installed on them by default.

Bring up a Windows ‘Command Prompt’, type the following command and hit ‘Enter’ on keyboard, that’s it, you are done!

%windir%system32inetsrvappcmd set config “http://localhost/Exchange” -section:system.webServer/security/requestfiltering -allowDoubleEscaping:true /commit:apphost

You will see the following response after running the above command in the same window.

Applied configuration changes to section “system.webServer/security/requestFiltering” for “MACHINE/WEBROOT/APPHOST/Default Web Site/Exchange” at configuration commit path “MACHINE/WEBROOT/APPHOST”

After running this command, you don’t need to restart any services on server, just run the command and ask your Entourage users to see if the issue has been resolved for them, at the most you can ask them to re-launch Entourage.

OR if you are a guy who is interested in details, then you can follow the manual steps outlined below.

Manual Steps
1. Bring up Notepad : File : Open, type%windir%System32inetsrvconfigapplicationHost.config in the ‘File name’ box, and then click ‘Open’.

2. Locate the section titled as:

<location path="Default Web Site/Exchange">

3. Under that section locate the tag

</authentication>

4. Just after that insert the following text on a new line:

<requestFiltering allowDoubleEscaping="true" />

5. Save the file and ‘Exit’ Notepad

Again, no restart of any service is required.