Hi, This is an intermittent error that occurs when the user uses "Reply" or "Reply All". Not sending a new message.
The error appears when the user clicks "Send" and when the user clicks ok to acknowledge the error, the message apppears to be sent ok but does not appear in the sent messages. The message is not received by the intended recipient and the message body is lost, causing the user to retype and resend the message.
I have set up error logging within Outlook and it does not even log the attempted send of the message or show the error at all.