Focus on segmentation and progressive profiling rather than sending more emails. The goal is to send the right message to the right person at the right time. Use progressive profiling to gradually learn more about your subscribers and tailor content accordingly. I built a referral program for a luggage brand that integrated with post-purchase email flows and grew a newsletter from 0 to 180K subscribers in 11 months using only organic promotion. We increased lead-to-subscriber conversion by 34% just by optimizing our form strategy. Quality of targeting matters far more than quantity of sends.