Sponsor This Newsletter - 100+ newsletters ready to promote your product
Kickstart Side Hustle Newsletter - Dwarf-size newsletter with viral marketing case studies
LetterHunt - LetterHunt connects you to 10,000+ niche, active newsletter writers to promote your product.
Sponsor My Tribe - These newsletters just want to promote your product/service
Newsletter Crew - Podcast, blog, and community for newsletter creators.
Vox Sentences Newsletter - Daily summary of the news in an easily digestible format