On Oct 8, 2019, at 10:58, Julian Koh (Redacted sender "kohster" for DMARC)
About a half hour later, I got another email from the same vendor asking if I
had time to talk, and his email message quoted what looked like a message
from me saying that I had read the message! I never got a Read Receipt
notification in Apple Mail, and I looked through the raw source of the
original message and didn’t see any linked content or read receipt headers in
it either. So I have no idea how this vendor got notified that I had
actually read the message.