Tracking pixels are routine in emails, not just websites, so the article is incomplete as it does not address how to guard against those.
One side effect is that Capital One thinks that it has the wrong email address for me:
"You haven’t opened an email from us lately,
so we’re checking in to make sure your contact
information is up to date."
Those are my favorite kind of spams.
Set up an email filter based on the Subject line to trash them.
1. https://www.fastmail.com/blog/fastmail-keeps-you-safe-from-s...