The ideal would be where all the content of value is in the email itself. The newsletter in that case either has entirely original content or useful commentary about or analysis of the news in the given niche or industry. A couple of examples of that:
But that’s super difficult to create, right? It’s essentially writing original thought leadership articles to send out rather than to post on your own site.
Somewhat easier is the curation approach where you send a digest of valuable reading. But I think that only works if the email contains more context about what these articles are and why the recipient would find them interesting.
Looking at the examples below, it seems they at least have an excerpt/summary from the article and are much less likely to have the feature/header image.
In a few cases, the summary is itself an original creation particularly for the newsletter recipients. Again . . . more work.
The newsletters from https://redef.com/ do a good job of giving context.
In the edtech world, EdSurge’s are must reads.
Finally, CBInsights is a good example of a digest that’s promoting their own content but by situating all that content within an original message to the email recipients.
At a minimum, look at the GrowthHackers.com top posts digest. It’s similar to yours as a digest of articles curated by the platform. But, again, excerpts rather than vague feature images.