Delivery error 554 5.4.4 received by Tech's on cell phones
We have 40 techs in the field. We email jobs from the AS400 to each tech's AT&T cell phone. Several times during the week, (no consistent) we will not receive the tech's response. Several hours after they tech replied to the email from us, they receive an undeliverable message "554 5.4.4 Internal Domain Look Up failed". This never happens with the tech's who reply with their gmail accounts. This is problem is becoming more frequent and causing frustration with the tech's. I have called AT&t Cell Department, Windstream - our internet provider...No one has a clue.