There are a bunch of services for this, for example https://www.kill-the-newsletter.com/
Or just google "email to rss"
If you still want to keep a copy in our email you can set a filter to forward the emails to those services and then archive them. Gmail supports forwarding & auto-archiving based on filters.
For more RSS questions you can also ask in /r/rss
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I reduced reading general news (multiple steps). First daily newsletter, then only a weekly magazine. I did this after noticing that I started to read more news on my Kindle as books.
I understand. You are facing the same problem as /u/gwern. I'm an inbox zero freak though ;) I've noticed an RSS link in the mailchimp link you've provided :P I'd rather use that than spamming your subscription box with kill the newsletter type of services. You can say I'm now a "p-zombie" like subscriber ;)