I inadvertently forwarded a message from a colleague's machine and, if he finds out, I'll be extremely embarrassed. Can I remove the blue arrow icon from the message line in the Inbox that shows that the message was forwarded?
You can't make a message revert from the icon that shows it was forwarded or replied to back to the original plain envelope icon. However, you can replace the blue forwarded arrow icon with the red replied to icon. Assuming you still have access to the colleague's Inbox, create a reply to the message but don't send it. Instead, save it. Outlook should change the message icon to the replied to icon immediately, but check the Inbox to make sure. After the icon changes, you can discard the reply.