I see this happening when replying to emails with external addresses in the CC: field. Out of four external addresses in the reply to all, one may be formatted as in your example, with no righthand angle bracket, and the /O= in its place. In the examples I've seen, the address affected seems to be the last. I thought at first that the sender had not done a reply to all but had copied and pasted addresses from another message, and had failed to include the closing angle bracket on the last address. However, the staff member did not copy and paste the recipients, or attempt to remove a recipient from the reply to all. Also, if I copy the address as you provided into the To: field of a new message, it is corrected by the router task to fredflintsone@bedrock.net.