SharePoint Alerts Work for some AD groups but not others

If I set up alerts for a list using an AD security group that has an E-mail set up in Exchange it works for some groups but not others.  You have to check a setting on the Exchange side per this info:

I know Exchange has an option to set distribution groups to only be available for use by "authenticated or trusted senders" (this prevents email/spam from the internet from being sent to internal distro groups). We ran into this problem, because SharePoint does not "authenticate" to the Exchange server, it is not, by default, trusted/authenticated.

Once you allow the distribution group in exchange to receive emails from un-authenticated users the Alerts will work.