Exchange ActiveSync and issues with “Attachment download” (with solution)

There was a frustrated voice came from other side of the world "Taiwan", said "I can’t download attachments on my Windows Mobile device, why are you guys blocking the attachments? This is very frustrating. what’s the point having a device that handles whole office documents? It’s not only me, all of my co-workers have same issue."

So there I am, blinking. I confirmed him that we don’t block attachments in Exchange ActiveSync, by the way I am using it all the time means I am downloading Office documents on my mobile. I did a short test and I could download any attachment from Mail.  But he can’t download any attachment from any Exchange mail. But he can download attachments from Google mail setup in Pocket Outlook.

Let’s begin the troubleshooting process.

Our setup is like below,


Now any USA user have no issues downloading attachments. But our foreign users complaining they can’t download attachments in any Windows Mobile devices.  I suspected some kind of "language" issue here. I am sure our Taiwanese users using Chinese language in mails.  I asked the user to turn on the ActiveSync logging (ActiveSync program on the device: Open Menu–>Options–>Exchange Server–>Settings–>Advanced Settings–>Event logging set to "Verbose") and send me the logs (in Device WindowsActiveSync*.*). He did send me the logs. 

ActiveSync on his device is getting "Attention Required" and clicking it displays "One or more of your attachments failed to download. To try downloading this attachment again, mark the…."

Attachment Error1












ActiveSync Log file on the device (MicrosoftExchange1.txt) says,

=-=-=-= Server Response =-=-=-
HTTP/1.1 500 ( The request was rejected by the HTTP filter. Contact your ISA Server administrator.  )
Connection: close
Pragma: no-cache
Cache-Control: no-cache
Content-Type: text/html
Content-Length: 2022

I checked the ISA server logs and found this,

Denied Connection CORPISA 9/13/2007 2:53:31 AM
Log type: Web Proxy (Reverse)
Status: 12217 The request was rejected by the HTTP filter. Contact your ISA Server administrator. 
Rule: RPC-OMA-ActiveSync Publishing
Source: Internal (
Destination: – (
Request: POST
Filter information: Req ID: 08f16710; Blocked: URL contains high-bit characters
Protocol: https
User: anonymous
Additional information
Client agent: MSFT-SPhone/5.2.203
Object source: Processing time: 1
Cache info: 0x8 MIME type: –

Blocked: URL contains high-bit characters!!!! Blocked???? What? High-bit characters?? What’s that?

Little bit of research I found when using OWA/ActiveSync (or even SharePoint pages), URL may contain double-byte character set (DBCS) or Latin-1 type. It happens to the user is using different language other than English. YES, Obviously my user is using Chinese character set in his Outlook and mails (even attachment names) has Chinese characters. Make sense.


  1. Open your ISA server console
  2. Click Firewall Policy on the left pane
  3. Right click on the firewall rule that serves "ActiveSync" and select "Configure HTTP"
  4. Uncheck "Block high bit characters" (see screen shot below) and click OK to close the dialog
  5. Click Apply the new settings take effect
  6. Say "Voila" and Dance.


I found later the closest MSKB article for the same issue: You receive a "The request was rejected by the HTTP Security filter" error message when you try to open a message from an Exchange Server that is published in ISA Server

Search words: ActiveSync, Attachment, high bit character, Windows Mobile

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