Outlook is Slow Rendering HTML Messages

It's amazing how often a seemingly innocent action by the user and an update for a program can affect negatively another. In this case, it's MS07-027: Cumulative Security Update for Internet Explorer, released in mid-May. After installing that update, Outlook 2003 responds very slowly when typing HTML messages.

The problem in this case is two-fold. First, users either added a large number of sites to IE's restricted zone or installed a "security" application (of the spy bot type) that added them. The cumulative security update then changed the way the Internet Explorer 7 rendering engine interacts with the Restricted Sites zone and this change causes Outlook to pause after each keystroke while the IE7 rendering engine checked the sites in the zone.

The user has several options to fix this issue:

1. Remove the security update.
2. Switch to plain text formatted messages. Using RTF message format will fix the problem but should only be used when all of your recipients use Outlook.
3. Remove all of the unnecessary sites from the Restricted zone.
4. Use Word as the email editor.

Of these options, removing the security update should be the last resort. Editing out the chaff in the Restricted zone would be my first choice since too many users load it with sites they are unlikely to ever come across and which may no longer be "live". I'm a big fan of short blocked or restricted lists and long safe lists, so I would tighten the Internet zone and use the Trusted zone for the sites I visited often.

The advantages of using short restricted lists and longer safe lists is that too often the restricted address is only in use for a limited time before the webhost shuts it down. In the case of email addresses, so many spammers fake the sending address or only use them once. In either case, the software reads the list as needed, which slows down the response for the very few times it hits a valid entry. Safe lists, while long, are still much shorter than blocking every untrusted address in existence.