Frances,
The word "formatting" was in a large bolded font. His signature was
large and red!
I think your member is confused about formatting.
If that word was large and bold then only the member could have done that (I think, not sure if a moderator could change the format by editing in pending). So at least from what I read he WAS NOT posting in plain text.
Some factors I can think of that may apply:
1) How did the member post? Via the group's New Topic or Reply buttons? Via a webmail service? Via a mobile device app? Via an email client on a PC?
2) Has the member set a Signature in his Subscription page? Is it set to HTML? Has he checked the box corresponding to how he posts (1)?
It is probable that having set an HTML signature in the Subscription page, a message the member sent as plain text would be converted to HTML in order to add the signature. But that still doesn't explain how a word in the non-signature portion of his message became specifically formatted. That would seem to give the lie to the member's claim of posting in plain text.
This message, like nearly all of mine, is being posted from an email client in plain text format. I don't have any signature set in my Subscription, nor does GMF force HTML, so I anticipate no shenanigans.
Shal