Multiple browser windows open when you click on a mailto: link:
http://windowsxp.mvps.org/MailtoProtocol.htm

1. http://www.oehelp.com/oedef.aspx; then...

2a. http://www.oehelp.com/oelnk.aspx

2b. (WinXP) [Control Panel Add/Remove Programs ] Set Program Access and
Defaults Email ...

If still no joy, see:

Installing OL updates changes the default mail handler from OE to OL
http://www.oehelp.com/OETips.aspx#13

SendTo and E-mail Links Do Not Work Using Outlook Express as Default
http://support.microsoft.com/?kbid=306098
--
~Robear Dyer (PA Bear)
MS MVP-Windows (IE/OE, Shell/User, Security), Aumha.org VSOP, DTS-L.org

VA Dave wrote:
I am having problems in making OE6 my default email program. Also, I am
having the problem of multiple IE windows (55 to be exact) popping up
when I click on an email link in IE6.

I have tried the following suggestions but nothing has worked:

http://www.microsoft.com/windows/IE/.../oerepair.mspx

http://www.oehelp.com/oedef.aspx

http://support.microsoft.com/?kbid=306098

When I click on the "Make default" button in OE6 under Tools/Options, the
setting is not saved then next time I back into Tools/Options.

Finally, I believe that the mailto key in HKEY_CLASSES_ROOT is corrupted
because when I click on it, I get the following message "Cannot open
mailto: Error while opening key". I cannot delete the mailto key either.

I would appreciate your help for fixing this problem. Thanks.