Outside of the immediate reservation confirmation emails, the rest of the reported email issues have nothing to do with the website itself. The website has no code or interactions with the back end processes that run to send the other types of email communications in other words. So the "Your vacation is just around the corner" type emails, or sales/marketing emails, etc., are all generated via back end processes only. It makes sense that if you change your account's primary email address to a different email, might result in changing the behavior since the kicks off a change to your account (at least in theory), that updates the back end systems.
There's also the "Primary point of contact" data that is not editable online. This is displayed under your My Ownership section of the Owner Dashboard area.
View attachment 104388
Changes to this data (and yes - I just logged in and mine is blank at present - it wasn't blank yesterday LOL) - require a phone call into Wyndham. For those of you who aren't receiving certain kinds of email communications, it might be worth calling into Owner Services and ensuring that your Point of Contact data is correct.