What are the best email warmup tools?

The 6 warmup options, side by side

All prices are list prices as of September 2026 (MailReach: October 1, 2026), taken from each vendor's pricing page (links in Sources). Plans change often, so check before you buy.

Swipe to see more →

Our take: if you're choosing a sender anyway, pick one with warmup included and spend the difference on better data. Compare the senders head to head in Instantly vs Smartlead vs Lemlist.

When should you skip each one?

One skip line per tool in the table.

• Instantly: skip it as a warmup pick if warmup is all you need. It's a sender, and Growth caps you at 5,000 emails a month.
• lemlist (lemwarm): skip it for warmup alone. lemwarm isn't sold on its own, so you'd be buying the sending plan.
• Smartlead: skip Base and Pro if you want the top warmup pool. Premium starts at Unlimited Smart ($174 a month billed monthly).
• MailReach: skip it if your sending platform already includes warmup. Per-mailbox pricing grows with every inbox you add.
• Warmup Inbox: skip it past a handful of inboxes. Basic's $15 per inbox a month and 75 warmup messages a day multiply with every mailbox.
• Warmy: skip it if you want a published per-mailbox price. It lists only "plans starting from $49/month" and prices by warmup volume.

What does a standalone warmup add to your monthly bill?

The inbox count is the number people forget. Warmup Inbox Basic is $15 per inbox per month, billed monthly. At our stack sizes (4 inboxes per rep, 2 inboxes per domain), layering it on top of a sender that already includes warmup looks like this:

Swipe to see more →

The stack totals are the monthly-billing figures from our cheapest cold email stack. Paying twice doesn't warm an inbox twice as fast. Warmy has no published per-mailbox price, so get a quote at your inbox count before you compare. For what Warmy adds and what its floor costs a year, see is Warmy worth it?; to check whether a listing is hurting you, see how to check if your domain is blacklisted.

Do I need a standalone warmup tool? (the 60-second test)

Probably not. Run these five questions in order and stop at the first "yes" that gives you an answer.

1. Does your sending platform include warmup? If yes, turn it on and stop here. Paying twice doesn't warm an inbox twice as fast.
2. Are you sending from a tool without warmup (a CRM, a basic mail merge, a plan tier that excludes it)? If yes, buy a standalone tool. Per-inbox pricing (MailReach, Warmup Inbox) fits 1 to 10 inboxes best.
3. Do you need proof of where your emails land (inbox, promotions, spam) before every campaign? If yes, pick a standalone tool that bundles placement or spam tests (MailReach, Warmy).
4. Are you running 20+ inboxes across several domains or clients? If yes, look at bundled warmup on a high-volume sender plan first, then price a volume-based standalone tool against it.
5. Is your problem actually bounces, complaints or missing DNS records? If yes, no warmup tool fixes that. Go to the next section.

Still unsure? Map your whole setup layer by layer (domains, inboxes, warmup, verifier, sender) with Pick the Stack.

Do you still need warmup in 2026?

Yes, for any new domain or new inbox. Warmup builds sending history gradually, so mailbox providers see a normal pattern instead of a brand-new address blasting strangers. It's cheap insurance, and most senders include it anyway.

What warmup can't do is rescue bad fundamentals. Treat it as one factor out of several, and not the biggest one:

• Authentication comes first. Google requires SPF, DKIM and DMARC for bulk senders (roughly 5,000+ messages a day to Gmail), according to Google's Email sender guidelines. Set all three up on every sending domain, even below that line.
• Complaints kill domains. Google and Yahoo require a spam complaint rate under 0.3%, and Google's target is under 0.1% (Google Email sender guidelines; Yahoo Sender Hub). No warmup network outvotes real people clicking "report spam."
• List quality matters more than warm-up replies. Our guideline is to pause above a 2% bounce rate; Google and Microsoft publish no bounce threshold. Verified lists bounce less, so verify before every send. Clean your list with a tool from our email verification guide.
• Relevance keeps complaints low. An email that fits the reader's problem gives them no reason to hit "report spam." Here's the formula: cold emails that work.

When a warmup vendor promises better inbox placement, open rates or reply rates, read that as vendor-stated. Those claims come from the vendor's own customers and aren't independent tests.

How long should warmup run?

Our guideline: at least two weeks of warmup before the first cold email, and then keep warmup on after you launch. The two-week figure is the Pipe Playbook rule, not a published benchmark. We haven't found a mailbox provider that publishes a required warmup period.

What the sending platforms say about warmup after launch:

• Smartlead's warmup guide says to keep warmup enabled after campaigns start, and that warmup volume goes down automatically as campaign sends go up.
• Instantly's warmup guide (updated September 11, 2026) says not to stop warmup when you start prospecting, and to lower it to a small daily baseline once outreach volume is consistent and placement is predictable.

Neither source says to switch warmup off, and neither says when to lower it. Our guidance: keep warmup on until real replies are steady, then lower the volume. That second half is our judgment, not a vendor rule.

Here's the ramp we recommend:

Swipe to see more →

Need more than 30 a day? Add inboxes and domains instead of pushing one inbox harder. The pipeline calculator shows how many sends you need for your meeting goal, which tells you how many inboxes to warm.

What should a warmup tool actually do?

It should send and receive realistic emails from your inbox, pull them out of spam when they land there, and show you a reputation trend over time. Everything else is a bonus.

Checklist before you pay:

• Works with your provider (Google Workspace, Microsoft 365, or both)
• Lets you set daily warmup volume and ramp speed
• Shows where warmup emails land, not just "health: good"
• Flags DNS problems (SPF, DKIM, DMARC) and blacklist hits
• Charges per inbox or per volume in a way you can predict at 3x your current size
• Has a free trial, or is already included in a plan you pay for

Which warmup setup should you choose?

Match the setup to your situation, not to the longest feature list.

• Solo founder or first SDR, 1 to 3 inboxes: use the warmup inside your sender (Instantly or lemlist). Zero extra spend. Build the rest of the setup cheaply with our cheapest cold email stack.
• Small team on a sender without warmup: a per-inbox standalone tool (MailReach or Warmup Inbox). Do the math per inbox before you sign.
• Agency or high-volume team, 20+ inboxes: bundled warmup on a high-volume sender plan (Smartlead Unlimited Smart or an Instantly plan), with a standalone placement tool only if you need client-facing reports.
• You keep landing in spam despite warmup: stop buying tools. Check authentication, bounce rate and complaint rate first.