Best email warmup tools: six options sorted by how they bill and what they include

Best email warmup tools compared: sort by how you pay and what you need

This page groups tools instead of ranking them, because the right pick depends on how many mailboxes you warm and whether you already pay for an outreach platform. Six warm-up options are read from their own pages as of October 23, 2026, and amounts are left to those pages.

Read vendor numbers with care. Every network size below is the vendor's own. Under the FTC's endorsement guides (16 CFR 255.2), an advertisement that features a customer result is likely read as typical, so the advertiser should hold substantiation for it.

The shortlist: what each tool is

• Warmy: plans covering several mailboxes, sized by warm-up volume, with placement tests, DMARC monitoring and verification. The vendor puts its network at over 1 million mailboxes and offers a seven-day trial. See the Warmy review.
• MailReach: billed per mailbox, with up to 100 warm-up emails a day per mailbox and spam test credits. It says its network is 30,000+ Google Workspace and Office 365 inboxes.
• Warmup Inbox: billed per inbox with daily message caps of 75, 250 or 1,000, a free plan of 15 warm-up messages a week and a seven-day trial on paid plans. It says its network is 30,000+ inboxes.
• Instantly: warm-up bundled with its outreach platform. Its Growth plan lists unlimited accounts and unlimited warm-up, and its slow ramp starts at 2 warm-up emails on day one.
• Smartlead: warm-up inside its outreach platform, described as a private pool that admits vetted senders, with automatic pauses on bounce spikes.
• lemwarm: part of lemlist's deliverability setup, which caps daily sending per inbox.

Placement testing and monitoring are a different job

Warm-up generates engagement. Placement tests and monitoring tell you where mail lands and why. Folderly is a suite of separate products for placement checks, monitoring, DNS and authentication inspection and DMARC reports, with plans that vary by product. Warmy and MailReach bundle tests with warm-up. Warmup Inbox offers a free placement test without sign-up.

For Gmail recipients, Google Postmaster Tools is the Google-run source for spam rate, reputation, authentication and delivery errors. It covers only mail sent to personal Gmail accounts, and the domain must be verified with a DNS record before data appears.

When no paid tool is the best option

Google advises senders to start with a low volume to engaged recipients, send at a steady rate and raise volume slowly, and its guidelines page gives no fixed schedule. Mailgun argued on July 20, 2026 that automated warm-up networks mostly fail to deliver what they promise, and it also sells sending, so it has an interest of its own. MailReach, which sells warm-up itself, says senders who have stayed under about 20 cold emails a day per inbox, or who email only existing customers or warm leads, might not need warm-up.

A paid tool earns its place with many mailboxes, a fast ramp or client work. For one mailbox, the free route in how to warm up a new email domain comes first.

Criteria: five questions that decide the fit

• How many mailboxes will you warm, and for how many months?
• Do you already pay for an outreach platform that includes warm-up?
• Do you need placement tests and DMARC monitoring, or only warm-up?
• Do SPF, DKIM and DMARC pass today? If not, fix that before any tool.
• Do the renewal and cancellation terms suit a short ramp? Read them before the trial ends.

Next step

Start with Warmy vs MailReach for a two-way comparison, read how Warmy bills to learn the plan structure, then run the free steps first.