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Why OWA Won't Open Some Messages
Take a close look at the browser version and the results of the IIS Lockdown tool.
by Ben Schorr and Jim McBee

July 26, 2004

Q:
For the past year, my users have been complaining that they can't open some messages through Outlook Web Access 2000. I haven't figured out why. Recently, my boss was working remotely and could not open an important message, so this problem has been escalated.

—Clayton, Osan, Korea

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A:
Ben: Problems affecting a boss somehow always seem to get moved to the top of the stack. Anytime someone reports problems with Outlook Web Access, I always suggest checking for the latest version of the Web browser. The latest version of Internet Explorer 5.5 is SP2 and 6.0 is SP1.

Jim: Without knowing a lot more about your problem, I can't say for sure, but I'm betting it is because you ran the Internet Information Server (IIS) Lockdown tool. This installs the URLSCAN.DLL that can cause this behavior.

Ben: Any message with specific characters in the subject may be filtered and prevent IIS from opening a message with those characters. The URLSCAN.DLL feature was designed to help prevent directory traversal by a hostile intruder. Character sequences that are blocked include two periods ("..").

Jim: You can allow specific URL sequences by editing the URLSCAN.INI file (shown in Figure 1). If you want to allow messages with a subject that includes periods, locate the [DenyUrlSequences] section of the file and place a semicolon in front of the line with the double periods ("..").

Q:
We have had to restore our mailbox store three times over the past year. Each time the backup stopped running and there were errors in the event log indicating a "-1018" error. Why is this happening?

—Troy, Las Vegas

A:
Jim: Ah, the dreaded -1018 error. This indicates a problem at the page-level of the EDB database file. Either the checksum written with the database page does not agree with the calculated checksum or a page pointer is incorrect.

Ben: If you are seeing one page-level error, there might be more in the database. Repairing the database is usually not the solution. Microsoft Product Support Services is going to always recommend restoring from backup because you really don't know how much of the database is damaged.

Jim: Contrary to popular belief, Exchange is not responsible for -1018 errors. Page-level errors usually occur after Exchange instructs the server to write data to the disk. Once you see a -1018 error, it will usually recur if you don't correct the root problem. The most common solutions to keeping a -1018 error from coming back is to make sure that you have up-to-date device drivers and firmware for your disk adapters.

Ben: Don't overlook the fact that the database corruption might be caused by outside interference such as a file-based antivirus product. Always make doubly sure that your file-based antivirus scanning software is not scanning the database folders, transaction log folders, or the queue folders. If you are using Exchange 2000, make sure that the file-based antivirus software is not scanning the M: drive.

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