How we make this list: we compare pricing pages, product documentation and public user reviews. Ratings come from G2, Capterra or Trustpilot, with the date we checked them.
Key takeaways
- Per-inbox pricing is a trap at scale: Lemwarm at 10 inboxes costs about $290 per month, while Instantly covers unlimited inboxes for $47 per month.
- The break-even point sits near three inboxes: below that, per-inbox tools win on simplicity; above it, unlimited models win every time.
- Independent placement tests put TrulyInbox at 98 percent primary inbox, Lemwarm at 96 percent, Folderly at 96 percent and Smartlead at 97 percent on one test.
- No warmup tool protects reputation after you hit send: one bad batch with spam traps or a 5 percent bounce rate can undo weeks of warmup overnight.
Quick comparison
| Tool | Best for | Starting price | Free plan |
|---|
 Instantly | Warmup bundled with cold email | $47 per month (Growth) | No |
 Lemwarm | Teams already using Lemlist | $29 per inbox/month | Free with Lemlist |
 Smartlead | High-volume senders on many mailboxes | $39 per month | Free trial (14 days) |
 Warmbox | Control over the ramp curve | $15 per month (Solo, billed annually) | No |
 Warmup Inbox | Blacklist monitoring and delisting | $15 per inbox/month (billed annually) | No |
 TrulyInbox | Free tier and unlimited mailboxes | $0 | Yes |
 MailReach | Standalone warmup with placement testing | $19.50 per mailbox/month | No |
 Folderly | Enterprise deliverability programs | $96 per mailbox/month | No |
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#1Instantly
Best for: Warmup bundled with cold email4.8/5 on
G2 (4,161 reviews, checked Oct 2026)
Visit instantly.ai
Starting price$47 per month (Growth)
Free planNo
Instantly bundles unlimited warmup with its cold email platform, so teams already sending through Instantly pay nothing extra to warm every inbox. The Growth plan costs $47 per month, with one comparison citing $30 per month on annual billing, and the warmup network spans over 1,000,000 accounts. Independent tests put Instantly at 92 to 95 percent primary inbox placement.
The catch is bundling: there is no warmup-only plan, so teams using another sending tool pay for a platform they do not use. Instantly fits teams sending cold email through Instantly itself, where warmup is effectively free at any inbox count.
What we like- Unlimited warmup on every plan
- 1,000,000-plus warmup accounts
- Bundled with a full cold email platform
Watch out for- No standalone warmup-only plan
- Placement scores vary across independent tests
Starting price$29 per inbox/month
Free planFree with Lemlist
Lemwarm is the warmup tool for teams already running Lemlist, with deep integration into sequences and a network of over 20,000 real inboxes. Independent tests from two sources both put it at 96 percent primary inbox placement with only 4 percent landing in spam, among the most consistent scores in this list.
Per-inbox pricing is the limit: $29 per inbox per month, or $24 on annual billing, means 10 inboxes cost about $290 per month. Lemwarm fits Lemlist users with a handful of inboxes who value placement consistency over unlimited pricing.
What we like- 96 percent primary inbox in two independent tests
- Deep Lemlist integration
- 20,000-plus real inboxes
Watch out for- Per-inbox pricing scales badly
- $290 per month at 10 inboxes
#3Smartlead
Best for: High-volume senders on many mailboxes4.5/5 on
G2 (448 reviews, checked Oct 2026)
Visit smartlead.ai
Starting price$39 per month
Free planFree trial (14 days)
Smartlead bundles unlimited warmup with its cold email platform from $39 per month, or $32 on annual billing, with a curated private network and agency-friendly white-label client portals. One independent test put it at 97 percent primary inbox placement, the highest score in that comparison, though another test measured 91 percent.
That variance is a reminder that placement scores depend on test conditions, not just the tool. Smartlead fits agencies and high-volume senders running many mailboxes who want unlimited warmup inside their sending platform.
What we like- Unlimited warmup on every plan
- 97 percent placement on one test
- Agency-friendly white-label portals
Watch out for- Placement varies across tests, down to 91 percent on another
- Bundled with a sending platform
Starting price$15 per month (Solo, billed annually)
Free planNo
Warmbox is the budget standalone pick, from $15 per month on annual billing or $19 monthly, with control over the ramp curve that lets operators tune how fast sending volume rises. Its network spans 35,000 inboxes, and setup is set-and-forget simple for solo operators.
Placement tests put Warmbox at 90 percent primary inbox with 10 percent in spam, the lowest score in this list, and plans cap at 6 inboxes on Growth. Warmbox fits solo operators with one or two inboxes who want cheap, simple warmup and accept lower placement scores.
What we like- Cheapest standalone entry
- Control over the ramp curve
- 35,000 inboxes in the network
Watch out for- 90 percent placement in tests, lowest here
- Plans cap at 6 inboxes on Growth
Starting price$15 per inbox/month (billed annually)
Free planNo
Warmup Inbox stands out for blacklist monitoring and automated delisting, which matters when a domain lands on a blocklist and needs removal, not just warming. ESP-specific warming for Gmail, a network of over 30,000 real inboxes, and detailed analytics round out a simple standalone tool from $15 per inbox per month on annual billing or $19 monthly.
Per-inbox pricing scales badly: 25 inboxes cost $475 per month. Warmup Inbox fits beginners and small teams with few inboxes who want blacklist monitoring alongside warmup, and who value simple setup over unlimited pricing.
What we like- Blacklist monitoring with automated delisting
- ESP-specific warming for Gmail
- 30,000-plus real inboxes
Watch out for- Per-inbox pricing scales badly
- $475 per month at 25 inboxes
Starting price$0
Free planYes
TrulyInbox offers a free tier plus unlimited mailboxes on every paid plan, from $22 per month on annual billing, with granular per-inbox reporting that analytics-focused users appreciate. One independent four-week test put it at 98 percent primary inbox placement with only 2 percent in spam, the best score in that comparison, across a network of over 40,000 real inboxes.
The brand is smaller than Instantly or Smartlead, and support depth may differ. TrulyInbox fits budget-conscious teams that want unlimited mailboxes and top placement scores without paying for a sending platform they do not use.
What we like- Free tier
- Unlimited mailboxes on every paid plan
- 98 percent primary inbox in one test
- Granular per-inbox reporting
Watch out for- Paid plans from $22 per month on annual billing
- Smaller brand than Instantly or Smartlead
Starting price$19.50 per mailbox/month
Free planNo
MailReach is the standalone warmup tool for teams that want placement testing built in, with anti-fingerprinting technology that keeps warmup emails looking human to mailbox providers. Placement tests put it at 93 percent on one test and 92 percent on another, consistently strong, and pricing starts at $19.50 per mailbox per month on annual billing.
Per-mailbox pricing means 25 mailboxes cost about $500 per month, so it suits small mailbox counts. MailReach fits teams that need placement testing and reputation monitoring as a standalone service, separate from their sending platform.
What we like- Anti-fingerprinting technology
- Built-in placement testing
- 93 percent placement in one test, 92 percent in another
Watch out for- Per-mailbox pricing scales badly
- $500 per month at 25 mailboxes
Starting price$96 per mailbox/month
Free planNo
Folderly is the enterprise deliverability program, from $96 per mailbox per month, with spam-trigger analysis that finds what pushes emails into spam and a managed program approach rather than a self-serve tool. Two independent tests put it at 96 percent primary inbox placement with 4 percent in spam, matching the best scores here.
The price is the highest in this list by far, and per-mailbox billing means even a small team pays hundreds per month. Folderly fits enterprises with deliverability problems worth a managed program, not small senders who need basic warmup.
What we like- 96 percent placement in two tests
- Spam-trigger analysis
- Enterprise deliverability programs
Watch out for- Highest price here by far
- Per-mailbox pricing
- Overkill for small senders
How we chose
We ranked tools on network size and quality, ramp control, blacklist and placement monitoring, price per mailbox, and active maintenance. Sources included a 10-tool warmup guide with vendor-site prices checked in July 2026, a cost-scaling comparison across inbox counts, and two independent placement tests running tools for three to four weeks. Placement scores vary by test, so the article reports both where sources disagree. We did not claim hands-on testing.
What to check before you sign
Do the inbox math first. At one inbox, per-inbox tools cost $15 to $29 per month and unlimited tools cost $30 to $47, so the difference is small. At 10 inboxes, per-inbox tools cost $190 to $290 per month while unlimited tools still cost $30 to $47. The break-even point sits near three inboxes: above it, unlimited models win every time.
Next, check what the tool measures. A green dashboard checkmark means little; real placement testing, blacklist monitoring and spam-trigger analysis tell you where emails actually land. Folderly and MailReach include placement testing, while cheaper tools may only report warmup volume.
Finally, protect the reputation warmup builds. Verify your list before sending, keep bounce rates under 4 percent, and never warm a domain just to burn it with spam traps, honeypots or outdated addresses. One bad batch can undo weeks of warmup overnight, and no warmup tool can repair that damage alone. Authentication matters just as much as warmup itself: set up SPF, DKIM and DMARC on every sending domain before you start, since mailbox providers distrust unauthenticated mail no matter how carefully it was warmed, and a missing DMARC policy is one of the fastest routes to the spam folder for a new domain.
Frequently asked questions
What is email warmup?
Email warmup gradually increases sending volume from a new or cold domain while simulating engagement, teaching mailbox providers to trust the domain so emails land in the primary inbox instead of spam.
How long does email warmup take?
Typically two to four weeks of gradual ramp-up before full sending volume, though timelines vary by operator, domain history and list quality. Rushing the ramp undoes the benefit, and a domain with prior spam complaints or a poor history may need longer, since providers remember past behaviour and restore trust slowly rather than all at once.
Is a free warmup tool enough?
For one or two inboxes, TrulyInbox's free tier or QuickMail's free warmup can suffice. For teams with more inboxes or deliverability problems, paid tools with placement testing and blacklist monitoring earn their fee.
Should I buy per-inbox or unlimited warmup?
Per-inbox tools suit one to three inboxes and simple needs. Unlimited tools suit four or more inboxes, since per-inbox costs scale linearly while unlimited plans stay flat. Do the math at your real inbox count.
Does warmup guarantee inbox placement?
No. Warmup builds sender reputation, but list quality, content, authentication and sending behaviour decide placement. A warmed domain sending to spam traps, purchased lists or bouncing addresses will still land in spam, no matter how long it was warmed.
What is the difference between warmup and deliverability?
Warmup is one part of deliverability: building reputation on a new domain. Deliverability also covers list hygiene, authentication, content, placement testing and blacklist monitoring, which is why enterprise tools like Folderly cost far more than basic warmup. Think of warmup as the foundation and deliverability as the whole house: a strong foundation helps, but it cannot compensate for bad lists, broken authentication, misleading subject lines or spam-trigger content.
Sources we checked (4)
- https://outreachbloom.com/email-warmup
- https://www.saleshandy.com/blog/email-warm-up-tools/
- https://roundproxies.com/blog/best-email-warmup-tools/
- https://skrapp.io/blog/email-warm-up/
Is your product missing or out of date?
We review this list regularly. Vendors can request a listing, send updated pricing or ask about featured placement.
Shihab Mia · Founder, Rankite
Shihab has 5+ years in B2B and SaaS SEO. He writes Rankite's software buying guides from pricing pages, documentation and public user reviews. More about Shihab.