We have had this problem since we originally set up exchange.
I have created a Distribution Group for example person1@company1.com wants to send emails from person1@company2.com (and receive them).
on the distribution group for person1@company2.com we have set the following;
Ownership: administrator
Membership: person1@company1.com
Membership approval: closed, closed.
Delivery management: senders inside and outside.
Group Delegation, email on behalf; empty, send on behalf; empty.
Why can person3@company1.com send emails as this person if they are not an administrator?
Any help would be greatly appreciated.
Thanks
Anthony