This isn't quite an Outlook question, however you could look at
the following MDSN link that explains a bit about it. I have a
feeling that a lot depends on How you are sending the mailings,
and what service provider and/or Server information.
Implementing Direct Mail Opt-Out:
http://msdn.microsoft.com/en-us/library/ms997142.aspx
You could also use
www.google.com and search for "Opt-Out Link"
for further information.
Nikki Peterson
