Bob,

          Thank heaven someone else is experiencing this.   For the longest time I had never encountered a Groups.io e-mail message that did not have what I call the "standard footer collection" at the bottom.  Suddenly, on at least one group, and possibly more (I only turn on individual messages for testing periods - I use the web interface) it's doing precisely what you describe.

           I have submitted a support ticket on this, and what I copied in as examples is virtually identical to what you've offered here, down to and including the "-=-=-=-=-=-=-=-=-=-=-=-" as the separator bar.

           Something's going wrong somewhere.

--

Brian - Windows 10 Home, 64-Bit, Version 1803, Build 17134 
     Explanations exist; they have existed for all time; there is always a well-known solution to every human problem — neat, plausible, and wrong.

          ~ H.L. Mencken, AKA The Sage of Baltimore