[VM] VM sending something other than text/plain?

[Terry Jones]

Today I had a weird experience. Someone Cc'd on an email I sent with VM
(8.2.0a) replied to me with a screenshot of the mail as he saw it in Gmail.
Some parts of the mail body had purple text, some black.  I'd composed the
mail after pasting text in from a bash window. You could see where I'd
typed new text.

It seems like VM must be sending that extra information. I've been using VM
for donkey's years and have never had anyone tell me my mails looked weird.
I've not changed my VM setup in months.  I tried sending the same person an
email containing several paragraphs, one of them pasted from bash, and he
could tell me which paragraph it was.

I don't see anything obvious to explain why this is happening (assuming it
*is* happening). I have vm-send-using-mime set to t, but its documentation
doesn't say anything about this. I've looked at the FCC log I keep of all
outgoing mail, and it just has a regular text/plain mail in it.

Can anyone shed any light on this?  I find it completely bizarre! So
bizarre that I can't quite believe it.

Thanks,
Terry