My verdict: the gold standard of email warm-up.
Mailreach is the reference when deliverability is critical. Premium in quality, premium in price. It's the TOP tool for deliverability and warm-up.
Quality is excellent, it's the reference. However, it gets expensive if you want to do a lot of volume (per-inbox pricing adds up fast). But if you want the best possible reliability, that's the price to pay.
What I like less: the price that adds up quickly when you have 10, 20, 50 inboxes to warm up. At scale, it becomes a significant budget. And some cold email tools now include warm-up (lower quality but sufficient for some).
My advice: if you do serious cold email and deliverability is your priority, Mailreach is the obvious choice. If you have a tight budget or few inboxes, first check if your cold email tool includes warm-up. For volume, calculate the total cost carefully before committing.