Controversial but with receipts, from 2 million sends through Fjordmail: median reply rate 1.8%, top decile 8.4%. The difference is never the tool. It is five things:
under 80 words (every 20 words over costs ~0.5 points of reply rate), one question, zero links in email one (links halve replies, send the link after they answer), a real observation in line one (not "loved your post about..." — something only a human noticed), and follow-up twice, then stop forever (email three converts, email seven annoys).
Warming matters less than list quality. A warmed domain sending to scraped garbage still burns. A fresh domain sending to 200 hand-picked prospects works. Buy lists never. Scrape carefully. Hand-pick always.