I will not promote. Newsletter still in the game?

people of startups, I want to know if newsletter are still relevant for your business? If you currently use a newsletter, I'd love to know: What made you start one? What problems has it helped solve? Has it improved customer retention, engagement, bookings, sales, or anything else? How often do you send it? If you don't use a newsletter: Why not? Have you considered it before? What stopped you from starting one? I'm researching how businesses are using newsletters today and would love to hear real experienc