How to stop spam emails from Amazon third-party sellers

Our family orders something from Amazon at least once a week. Increasingly, we order items from Amazon third-party sellers, many of whom honor Amazon Prime shipping and are almost indistinguishable to the common buyer throughout the entire purchase and delivery workflow. We have very few problems with third-party sellers, but there is one major difference between buying something Amazon-stocked and from a third-party supplier: the inevitable follow-up email that essentially puts the buyer on a mailing list they never opted into.

Here's one such email:

The email says that Dropcases "[tries] hard to send messages relevant to this transaction." This is great, but I'd rather never get any email from any third-party supplier. I have to unsubscribe to each and every one of these third-party supplier mailing lists, which is very annoying. If this 338-post discussion in Amazon's feedback forum is any indication, many people agree. I'd guess that the vast majority of Amazon users wish they could automatically unsubscribe from such emails, or better yet, never get them in the first place. The email also asks for a 5-star review, but after getting an email like this, I feel like leaving a 1-star review.

To mitigate this problem, I created a gmail filter that takes emails from "" that have the word "unsubscribe" in them and skips the inbox, marking as read. This at least prevents me from ever seeing this email.

I chose to include the word, "unsubscribe," in the filter because emails that come from "" that do not have "unsubscribe" in them seem to be correspondence with third-party suppliers, and I want these emails to show up in my inbox.