Here's the reality — Validity's 2024 Email Deliverability Benchmark (via MailReach) found one in six emails never reaches the inbox, keeping global inbox placement around 84%. Gmail's own baseline is 87.2% as of Q4 2024. A good warmup tool gets you back above that — but which tool is "best" depends on how many inboxes you're warming.
The Scale Question Drives Everything
Warmup tools split into two pricing models, and the math reverses depending on your scale:
- Per-mailbox tools (MailReach, Warmforge): cheap for 1–3 inboxes, expensive past that. Prospeo notes per-mailbox tools become "prohibitively expensive beyond five accounts."
- Unlimited platforms (Instantly.ai): higher floor, but flat for any number of mailboxes — wins at 4+ inboxes.
If you're warming a single founder inbox, go per-mailbox. If you're running a real outbound program with multiple sequencer inboxes, the unlimited plan is almost always cheaper.
The Tools, Honestly Priced
Instantly.ai — Growth plan at $37.60/mailbox/mo on annual billing (or $47/mo billed monthly), with unlimited warmup accounts. Skylead's independent placement test of ~200 emails put Instantly at 95% inbox placement — not a continuous score Instantly reports, but a strong data point. Best choice for teams warming 4+ inboxes.
MailReach — $25/mailbox/mo for 1–5 inboxes, dropping to $19.50/mailbox/mo at 6–20 inboxes. 4.7/5 on G2 from 44 reviews when Prospeo last checked. Built-in placement testing is the differentiator versus pure warmup-only tools. Best choice if you want one solid per-mailbox tool with monitoring built in.
Warmforge — $12/mailbox/mo monthly, $10/mailbox/mo quarterly, with two months free on annual. Cheapest per-mailbox option at 1–3 inboxes. At 10 inboxes you're at $100/mo — versus Instantly at $37 unlimited. Don't pick "the budget tool" without doing the multiplication for your inbox count.
Dashboards Lie — Test Independently
Prospeo documented a case where a RevOps lead ran Smartlead's warmup for three weeks — dashboard showed 100% reputation, green everywhere. Then an independent Emailguard placement test showed Gmail was dumping every message into spam. Don't trust the warmup tool's own dashboard as your only signal. Run an independent placement test (Emailguard, GlockApps, MXToolbox) every 2–4 weeks during warmup and before any high-volume campaign.