Ian, David, We've discussed endless loops but I'm not sure we have actually come to agreement. May I suggest we put this on the next Con Call agenda? Should we specifically not allow? 1. Ack on Ack 2. DeliveryReceipt on DeliveryReceipt 3. Error on Error 4. DeliveryReceipt on Ack 5. Ack on DeliveryReceipt 6. DeliveryReceipt on Error 7. Error on DeliveryReceipt 8. Error on Ack 9. Ack on Error I suggest we should not allow 1-6. Item 7 is probably OK. Items 8 and 9 are mutually exclusive, i.e. we can have either but not both (probably 8). Anyone else have an opinion? Regards, David Fischer Drummond Group