They do work to some extent (which is greater than zero). I have a newsletter to share links related to Python, Linux, Regular Expressions, Vim, etc. 38 issues

They do work to some extent (which is greater than zero). I have a newsletter to share links related to Python, Linux, Regular Expressions, Vim, etc. 38 issues later, I have close to 500 subscribers (I don't do pop-ups, but thanks for the reminder - I should at least add them in the footer of my blog posts, been promoting mostly to my readers on Gumroad/Twitter). Based on Gumroad stats, open rates are above 40%. I send 10-15 links per week, and the total link clicks average around 150 (not sure if adblockers affect such stats). I try to optimize links to share based on interest shown in topics so far. And as others have commented, one of the reasons to start a newsletter is to have your own platform for sharing content.