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Exchange Server 2010 SCL X-Headers

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  • Exchange Server 2010 SCL X-Headers

    Some of our hosted Exchange customers are receiving HTML emails with blank bodies after migrating them from Exchange Server 2003 to Exchange server 2010. The affected users are running Outlook 2010 and have locally installed AntiVirus and AntiSpam Outlook Add-ins. We've found that disabling the AntiVirus and AntiSpam Add-ins resolves the issue. This isn't a long term solution for us as we can't dictate to our customers what local AntiVirus and AntiSpam software and components they can and can't use and trying to do so would be cumbersome and difficult. These users did not have this problem on Exchange Server 2003. We believe that the problem is that the SCL Header in the email is triggereing the AntiVirus and AntiSpam Add-ins to strip the content from these emails. The SCL header wasn't present in Exchange Server 2003, so this makes sense to us. What we'd like to do is to remove the SCL Header when the message is delivered to the mailbox. We do not want to remove or ignore the SCL Header when the emails enter or leave the Hub Transport server from or to the internet, we only want to remove the SCL Header when the email is delivered to the mailbox. We do not want to disable Content Filtering. Is there a way to achieve this by using the Header Firewall or by using a Transport Rule?

  • #2
    Re: Exchange Server 2010 SCL X-Headers

    The reason it wasn't a problem with Exchange 2003 was because SCL headers were not written by default. You could see them if you made a registry change.
    Microsoft changed that behaviour with Exchange 2007 so that transport rules could manipulate headers.

    Unfortuantely you cannot do what you want to do. If you have content filtering enabled then you get SCL values written to the headers. The most you can do is remove them completely, but that will make the content filter for anything other than outright reject close to useless.

    The tools on the workstations aren't Trend by any chance? I have recently became aware that Trend have started using and manipulating the SCL values themselves.

    Simon Butler
    Exchange MVP

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    • #3
      Re: Exchange Server 2010 SCL X-Headers

      Thanks, Simon. We were afraid that we'd have to disable the Content Filter but were hoping for a way around that. We've got a case open with Microsoft PSS and are awaiting their input on this issue.

      The Clients are using AVG AntiVirus, but I've heard of the same problem using other AV packages as well.