Symptoms

When clicking on a mailto link in a web site, user gets error that says: Could not perform the operation because the default mail client is not installed properly

Cause

Outlook Express is set as the defualt mail client, and the mailto link has more than 456 characters

Resolution

In Internet Explorer, click on view, then Source

-In the HTML code, look for the list of email recipients.
i.e.: <A HREF="mailto:someone@somewhere.net,anyone@anywhere.net">visible
text</A>

-select the email address(es)
-copy the email address(es)
-close the notepad that opened w/ the source code
-open Outlook Express and click Compose Message.
-click in the To box, and then paste the email addresses you just copied

More Info

http://support.microsoft.com/?scid=kb;en-us;182985&spid=2578&sid=global