Post your Outlook version.

Here's how Microsoft says to do it in Outlook 2003.

http://office.microsoft.com/en-us/assistance/HP010271951033.asp

I am also having the same problem.  I can select some DL members t
send mail to using the "properties" tab in the distribution list i
Outlook 2000 and older, but newer versions don't seem to have this.
HELP

Microsoft's new "feature" (above) of clicking the PLUS sign next t
the list inside the "TO" window and then DELETING the unwante
addresses seems backwards and is not acceptable to our client

Any ideas...