Do note that this is actually documented as a workaround on our website in our Compatibility Center entry for Outlook 2003 and that the forum post you are responding to is 3 days away from being a year old.
The Compatibility Center Tip:
http://www.codeweavers.com/compatibility/browse/name/?app_id=152;tips=1
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With CrossOver 9.0.1, it is no longer necessary to add Internet Explorer 6 to the Outlook bottle to view or print html messages. It is further not necessary for cutting and pasting. In fact, we highly advise against adding Internet Explorer 6 to your Outlook 2003 bottle.
If some e-mails don't display in Outlook 2003 or you're having problems copy/pasting, try installing Internet Explorer 6.0 in the same bottle as Outlook. Also try disabling Word integration (Tools -> Options, Mail Format tab, un-check the Use Microsoft Office Word options) and restart Outlook.
Finally, try setting your display and edit options to something other than Rich Text.
If a message still does not display, try clicking on View -> Message Header.
If you are using CrossOver 9.0.1 or later and you still find it necessary to add Internet Explorer 6 to the bottle, we need to know. This is best served in the form of a ticket or an email to info@codeweavers.com.
We never added this to our Support Library because it is considered an 'unsupported' workaround. The addition of IE6 to any bottle makes that bottle much more difficult to debug. This means, if a bottle begins to have strange behavior, we cannot effectively look into it. IE6 should only be added as a last resort to resolve a problem like this and should only be added after consulting with our Support Team.
Also note that adding IE7 to a bottle with Office applications in it is highly untested. We have had reports that adding IE7 to an Office bottle actually disables some of the functionality. It is our intent that these items would not affect each other, but at this time we do not recommend this setting.
Our sincerest apologies for any confusion.