HTC One forums are talking about this problem, as is AT&T. As of Feb 17th, I am persistently unable to reply to received email or create/send new email with my Exchange Mail account. Deleted account, reestablished account, rebooted phone...all failed to resolve the problem. Error message states, "Unfortunately, Mail has stopped." Verizon, please help ASAP...unsatisfied customers are being impacted negatively.