The spam filter thing may very well be the reason.
That said, I only get emails from Aliexpress when I very recently visited it. Also, if you put some items in the cart for later, it will send you a reminder email that you have items in your cart and may want to finalize your order. That's not excessively annoying, just a bit pushy. Otherwise, it will occasionally send an email of "items you may like".
But there may be a way of stopping those mails actually, as someone said here, I'll have a look. I honestly never found Aliexpress emails to be so numerous or annoying that I would bother.