Hello NickLinc,
Sorry for late response for I was out of office yesterday.
It is hard to detect why the rule does not work. Since the purpose of these rules is to archive all emails but no read receipts. Could you please try this workaround?
In the rule which BCC to GFI, add an exception that do not apply this rule if the message is a read receipt.
Could you please try it and let me know the result?
Thank you.
George Wu