I have set some DL so only specific persons could sent e-mail to it but I've found that I could bypass this security if you chose the dl then click on the plus sign. How can I remove the possibility to click on plus sign ?

HOW TO: Hide Distribution Group membership http://exchangepedia.com/blog/2007/11/how-to-hide-distribution-group.html We use this method very much. BTW, The man behind the blog is one of the authors of this outstanding bookMicrosoft Exchange Server 2007: The Complete Reference (Paperback)http://www.amazon.com/Microsoft-Exchange-Server-2007-Reference/dp/0071490841 jas

Thanks Jon, this was exactly what I was looking for. Michel P.