There may be times when a contact does not want to receive any mail with the exception of a particular mailing preference.
E.g. the contact asks that they receive no mailing except for receipts.
Lookup Values under the Administration module has a setting whereby certain Mailing Preferences can be set to be excluded. See your administrator if the receipt is not excluded.
1.Set the contact as Do Not Mail (as described in Example 5 above).
2.The receipt will then appear with a green tick, if it has been setup as an exclusion under Lookup Values.