After spending some time on the phone with Microsoft Product Support Services (PSS) recently, I mentioned to the support technician that I was about to deploy Windows XP Service Pack 2 (SP2) to my network machines. The technician cautioned me to keep an eye on Outlook Web Access (OWA) performance. OWA uses pop-up windows for some of its functionality, and SP2's version of Internet Explorer (IE) includes a Pop-up Blocker.

I looked into the subject a bit more and was happy to find the Microsoft article "Description of the known issues with using Outlook Web Access on a Windows XP SP2-based computer" ( http://support.microsoft.com/?kbid=883575 ), which details the effects of SP2 on OWA. I also learned a lot from a post at jeffdav's WebLog ( http://blogs.msdn.com/jeffdav/archive/2004/06/21/161789.aspx ), a blog site by Jeff Davis (a member of the Internet Explorer team at Microsoft). If your organization uses OWA on the local intranet only, you don't need to worry about the Pop-up Blocker issue. IE automatically considers sites in its Trusted Sites and Local Intranet zones to be safe and doesn't block pop-ups for those sites. But if users access OWA from over the Internet, you might need to make some adjustments.

As the Microsoft article I mention above explains, the Pop-up Blocker's default filter setting of Medium blocks certain Exchange Server 2003 and Exchange 2000 Server OWA features. These features include new mail and reminder notifications, the New Folder command, the New Message button in the Find Names dialog box, and the "Send Mail to Contact" button on the Contact form. In addition, many context-menu commands (including Reply, Reply to All, Forward, Create Rule, and Move/Copy to Folder) for individual items in table views are blocked. Oddly, the Move/Copy button on the toolbar works fine. The "Open in New" context-menu command for folders is also blocked. The Microsoft article claims that the Attachments button in the Item dialog box doesn't work, but I found out otherwise. The first time I clicked this button, I received a blocked pop-up notification, but the second time I clicked it, it worked.

That's when I started looking into the information that Jeff Davis provides about the different Pop-up Blocker filter levels: High, Medium, and Low. I found that if I changed the UseTimerMethod value in the HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\New Windows registry subkey from 0 to 1, the Attachments button worked the first time. Typically, though, you won't want to change the subsettings for Pop-up Blocker filter. A better solution for OWA users who have control over their own Windows registry is to put the OWA URL in IE's Trusted Sites list or add it to the Pop-up Blocker's whitelist.

Temporarily turning off the Pop-up Blocker for the OWA site is another solution. If users connect to OWA via XP SP2 kiosk computers, they might be able to use this solution by clicking the Pop-up Blocker information bar that appears at the top of the IE window when a pop-up is blocked. Another option for users who log on with forms-based authentication would be to choose the Basic OWA interface rather than the Premium interface.

In addition to Pop-up Blocker issues, the Microsoft article documents some script errors (especially those related to name checking) that users might encounter and mentions that OWA for Exchange 2003 will no longer recognize the Secure MIME (S/MIME) control after you deploy SP2. The scripting errors disappeared when I added the OWA site to the Trusted Sites zone, but I was unable to find a workaround for the S/MIME control issue.