How do you approach email marketing when you want to sell products?

According to Neil Patel's data about influencer marketing, newsletter/email is the most effective channel when it comes to ROI (attached infographics; source)

But not so many influencers own newsletters; in most cases, only social media channels.

I also run my weekly newsletter, where I claim several sponsorships, but I usually offer it as a way of increasing awareness, as I do not consider myself an influencer.

P.S. I like the "invasive" approach to the company's newsletter by @Eight Sleep – they are consistent and are designing it very well.

I would like to know from the perspective of the companies/startups here:

1) How do you handle email marketing and possible collaboration with influencers who own a newsletter for distribution? If you are open to sharing what tactic helped you the most, I will be thankful. 🙏

2) What do you cover in your company's newsletter? (e.g. updates, interesting tricks, etc.)

3) How often do you sell your product directly?

(E.g. what are the common ways of placing/exposing your brand? I have in mind several options:
– specialised/exclusive article on a certain topic where the product is mentioned? (product placement)
– affiliate program via link within the newsletter?

– logo placement at a certain position with a link to your product?

– banner within the newsletter with a special offer/promo?