The ISA Firewall HTTP Security Filter Rejects Email Messages When Opened from a Published OWA Site

Have you ever tried to open an email message via an OWA site that has been published by an ISA Firewall and received an error message indicating that the HTTP Security Filter blocked the connection? If so, you problem saw something like this:

The page cannot be displayed

Explanation: There is a problem with the page you are trying to reach and it cannot be displayed.
Try the following:

  • Refresh page: Search for the page again by clicking the Refresh button. The timeout may have occurred due to Internet congestion.
  • Check spelling: Check that you typed the Web page address correctly. The address may have been mistyped.
  • Access from a link: If there is a link to the page you are looking for, try accessing the page from that link.

Technical Information (for support personnel)

  • Error Code: 500 Internal Server Error. The request was rejected by the HTTP Security filter. Contact your ISA Server administrator. (12217)

One reason why this might happen is that the message contained high-bit characters, as seen in non-English languages such as Spanish or German. You can fix this problem by configuring the HTTP Security Filter for the Web Publishing Rule to not block high-bit characters, as seen in the figure below.



Thomas W Shinder, M.D.


Email: [email protected]

MVP — Microsoft Firewalls (ISA)

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