The best way to grow a Newsletter is to cross-post it.
Are there newsletter writers that want to help each other grow with a cross-promotion?
I didn't see a post on this recently, so I'm sorry if I missed it.
Post your newsletter details here and reach out to the ones that fit in terms of subscribers and audience:
Here's a template we can copy/paste:
Here is mine,
Newsletter Name: Engineering Leaders Corner
Number of Subscribers: 1400+
Target Audience: Aspiring or Newer Engineering Leaders / Developers
Looking for: Cross promotion and sponsorships that has a similar audience
How best to reach out: me@kulkarniankita.com or DM!
Newsletter Name: blog.syntha.ai
Number of Subscribers: 210
Target Audience: AI/startups
Looking for: cross-promotion
Contact: https://twitter.com/den_volkhonskiy