A properly warmed domain lands 87% of cold email in the inbox. An unwarmed domain sending the same message lands just 12%. That 7x gap, documented in the 2026 Cold Email Benchmark Report, makes warmup the single biggest deliverability lever an agency can pull — bigger than subject lines, list quality, or sending volume.
The 10 tools below cover three pricing models: bundled warmup built into a sending platform (Instantly, Smartlead), standalone per-inbox tools that charge per mailbox (Lemwarm, MailReach, Warmup Inbox, Warmbox, Mailwarm), and flat-rate standalone tools that charge by total daily volume regardless of inbox count (Mailivery, TrulyInbox, Warmy.io). For agencies managing 10 to 50 client inboxes, the model matters more than the tool — per-inbox pricing that looks cheap at one mailbox becomes four-figure monthly spend at scale. This roundup compares published pricing and documented features as of October 2026; no tool was tested in a controlled environment, and benchmarks are cited with their source.
Comparison table
| Tool | Best for | Starting price | Pricing model | Warmup network |
|---|---|---|---|---|
| Instantly | Agencies wanting warmup + sending in one platform | $37.60/mo (annual) | Bundled with sending, unlimited mailboxes | Unlimited warmup on every plan |
| Smartlead | Budget all-in-one sending + warmup | $39/mo | Bundled with sending, unlimited mailboxes | Unlimited warmup on every plan |
| Lemwarm | Teams already using Lemlist for cold email | $24/inbox/mo (annual) | Per-inbox standalone | 20K+ healthy domains |
| MailReach | EU agencies wanting warmup + spam testing | ~$19.50/inbox/mo | Per-inbox standalone | Network of real inboxes |
| Mailivery | Agencies with many inboxes, flat-rate budget | $29/mo | Flat-rate, unlimited mailboxes | P2P network, 250 emails/day per inbox |
| TrulyInbox | Agencies wanting free tier + volume-based pricing | $29/mo (annual $264/yr) | Flat-rate, unlimited mailboxes | 2:1 warmup-to-cold ratio |
| Warmup Inbox | Solo operators on a budget | $15/inbox/mo | Per-inbox standalone | 30K+ real inboxes |
| Warmbox | Small teams with 1 to 6 inboxes | $15/mo (1 inbox) | Per-inbox standalone | Private inboxes network |
| Warmy.io | Large-scale B2B warmup with biggest network | From $49/mo | Per-inbox, demo-gated tiers | 1M+ real mailboxes |
| Mailwarm | Premium single-inbox with consulting | $69/mo (1 inbox) | Per-inbox standalone | 50K+ aged real inboxes |
Pricing verified October 2026.
The bundled warmup tools
Instantly
Best for: Agencies that want warmup and cold email sending in one platform, with no per-mailbox fees.
Instantly bundles unlimited email warmup into every sending plan. The Growth plan starts at $37.60/month billed annually ($47/month monthly) for 5,000 emails/month and includes unlimited email accounts and unlimited warmup. The Scale plan at $77.60/month annual covers 100,000 emails/month. Instantly also sells a separate Credit bundle for lead enrichment via its 450M+ B2B database, but warmup is always included in the sending plan, never an add-on.
Pricing verified October 2026 via instantly.ai/pricing.
Honest limitation: Instantly is a sending platform first, warmup second. Its warmup network is solid but not as deeply configurable as standalone tools — you cannot set industry-specific warmup content or granular daily interaction caps. If warmup is your primary concern rather than sending volume, a dedicated tool gives you more control.
Smartlead
Best for: Agencies wanting the cheapest all-in-one sending and warmup, with unlimited mailboxes from day one.
Smartlead includes unlimited warmup on every plan, starting at $39/month for the Base plan (2,000 active leads, 6,000 sends/month). The Pro plan at $94/month covers 30,000 leads. Annual billing saves 17%. White-labeling costs $29/month per client workspace, available from the Pro tier onward.
Pricing verified October 2026 via smartlead.ai/pricing.
Honest limitation: Email verification is a $59/month add-on on the Base and Pro plans, only included on the Unlimited tiers ($174 and $379/month). The warmup is functional but lacks the diagnostic depth of standalone deliverability tools — no inbox placement testing or spam-score monitoring is included.
The standalone per-inbox warmup tools
Lemwarm
Best for: Teams already using Lemlist for cold email sequences — Lemwarm is included free with every paid Lemlist plan.
Lemwarm charges $29/month per inbox on the Essential plan (monthly) or $24/month per inbox annually. The Smart plan is $49/month per inbox ($40/month annual) and adds personalized warmup emails and industry-tailored warmup networks. The warmup network spans 20K+ healthy domains with a 40 warmup emails/day cap on Essential.
Pricing verified October 2026 via toolradar.com cross-verification (lemwarm.com/pricing is JS-hydrated).
Honest limitation: Per-inbox pricing with no volume discounts makes Lemwarm expensive at scale — 10 inboxes costs $290/month on Essential, $490 on Smart. The Smart plan's "personalized warmup emails" and "industry-based warmup" are cosmetic features that sound good but do not measurably impact deliverability, per the MailReach competitor review. If you are not a Lemlist user, there are cheaper standalone options.
MailReach
Best for: EU agencies that want warmup and spam testing bundled together, with volume discounts for multiple mailboxes.
MailReach charges approximately $25 per mailbox/month at the entry level, dropping to ~$15 per mailbox at 25+ mailboxes. The all-in-one tier (warmup + spam testing) costs ~$19.50 per mailbox/month and includes 20 spam-test credits. Annual billing saves 20%. The free tier covers 2 inbox placement tests per month.
Pricing verified October 2026 via leadhaste.com cross-verification (mailreach.co/pricing is client-rendered).
Honest limitation: Spam-test credits are the hidden cost — heavy testing burns through the included 20 credits quickly, and additional credits cost $210 for 200. At scale, even the volume-discounted per-inbox pricing compounds: 50 mailboxes at the all-in-one tier runs ~$975/month. No free plan, only a trial period.
Warmup Inbox
Best for: Solo operators or small agencies with 1 to 3 inboxes who want the cheapest standalone entry point.
Warmup Inbox offers the lowest per-inbox starting price at $15/month for one inbox ($180 billed yearly). The Pro plan is $49/inbox/month and the Business plan is $79/inbox/month. A 7-day free trial requires no credit card. The network covers 30K+ real inboxes.
Pricing verified October 2026 via warmupinbox.com/pricing (full render).
Honest limitation: No inbox placement testing, no email verification, and no blacklist monitoring are included on any plan. The per-inbox price drops from your second inbox, but past 50 inboxes you need a custom quote. For agencies running 10+ client inboxes, the per-inbox model gets expensive fast compared to flat-rate alternatives.
Warmbox
Best for: Small teams with 1 to 6 inboxes who want a simple, no-frills warmup tool.
Warmbox offers three tiers: Solo at $15/month (1 inbox), Startup at $69/month (3 inboxes), and Growth at $139/month (6 inboxes). All plans include gradual or random warmup, a private inboxes network, and Gmail/G Suite OAuth integration. Annual billing applies a discount over monthly pricing.
Pricing verified October 2026 via warmbox.ai/pricing (full render) and cross-verified via leadhaste.com.
Honest limitation: No free trial — you commit before seeing results on your own inboxes. The per-inbox cost actually rises from Solo ($15) to Startup ($23/inbox) to Growth ($23.17/inbox), which is unusual; most tools reward volume. Beyond 6 inboxes you need a custom plan. No inbox placement testing or spam-score diagnostics.
Mailwarm
Best for: Single-inbox users who want premium positioning with deliverability consulting included.
Mailwarm charges $69/month for the Starter plan (1 inbox, 50 warmup emails/day), $159/month for Growth (3 inboxes, 200/day), and $479/month for Scale (10 inboxes, 500/day). Every plan includes provider-level warmup and expert guidance calls (1 call/month on Starter, 4 on Growth).
Pricing verified October 2026 via mailwarm.com/pricing (full render) and cross-verified via emailwarmup.com review.
Honest limitation: At $69/month for a single inbox, Mailwarm is among the most expensive standalone warmup tools on the market. Independent testing by emailwarmup.com showed a 55% inbox placement rate — below the 85% industry baseline without any warmup. No free trial, no diagnostic tools, and poor Outlook/Microsoft results per multiple G2 reviews. An agency managing 10 client inboxes would pay $479/month versus $29/month on a flat-rate tool.
The flat-rate standalone warmup tools
Mailivery
Best for: Agencies managing many client inboxes who want predictable flat-rate pricing regardless of mailbox count.
Mailivery charges by total daily warmup volume, not by inbox count. The Starter plan is $29/month (200 warmup emails/day shared across unlimited mailboxes), Professional is $79/month (800/day), and Business is $199/month (2,500/day). Annual billing saves 25%. A 7-day free trial is available. Every plan includes inbox placement testing, blacklist monitoring, email verification, and spam-word checking — features that per-inbox tools charge extra for.
Pricing verified October 2026 via mailivery.io/pricing (full render).
Honest limitation: The daily warmup volume is shared across all connected mailboxes, so an agency with 50 inboxes on the Starter plan gets only 4 warmup emails per inbox per day (200 divided by 50). You need the Professional or Business plan to warm a meaningful number of inboxes at an effective per-inbox rate. The 250 emails/day per-inbox cap limits aggressive warmup schedules.
TrulyInbox
Best for: Agencies that want a free tier and volume-based pricing with unlimited mailboxes.
TrulyInbox charges by daily warmup volume across unlimited mailboxes. The Starter plan is $29/month billed annually ($264/year) covering 200 warmup emails/day, the Growth plan is $84/month annual ($1,008/year) covering 1,000/day, and Scale is $169/month annual ($2,028/year) covering 3,000/day. A free tier covers limited warmup with AI Adaptive strategy only. The 2:1 warmup-to-cold ratio means every cold email sent should be matched by 2 warmup emails per day.
Pricing verified October 2026 via trulyinbox.com/pricing (full render).
Honest limitation: The free tier is limited to AI Adaptive warmup only — the other 3 strategies (Progressive, Random, Flat) require paid plans. The Growth and Scale plans are priced for total daily volume, so an agency with 20 inboxes sending 50 cold emails each (1,000/day cold) would need 2,000 warmup emails/day, which requires the Scale plan at $169/month. No inbox placement testing on the free or Starter tiers.
Warmy.io
Best for: Large-scale B2B senders who need the biggest warmup network and separate B2B vs B2C warming paths.
Warmy.io starts at $49/month with separate warming paths for B2B senders (Google Workspace and Microsoft 365 business inboxes) and B2C senders (Gmail, Yahoo, Outlook consumer inboxes). The warmup network is the largest in this roundup at 1M+ real mailboxes, with a 500K+ US seed list that rotates monthly. A custom plan with a dedicated success manager is available for enterprise senders. Warmy.io also includes a templates AI optimizer that scores and rewrites campaigns for inbox placement before sending.
Pricing verified October 2026 via warmy.io/pricing (full render). Specific tier pricing beyond the $49/month starting point is demo-gated and requires contacting sales.
Honest limitation: Warmy.io does not publish full tier pricing on its website — the $49/month starting price is visible, but the higher tiers (up to $279/month per third-party sources like frontdeskreview.com and findstack.com) are behind a "Book a demo" flow. This makes it impossible to compare exact costs without a sales call, which is a friction point for agencies that want to evaluate pricing before committing.
How to choose
Three questions that narrow the field fast:
Do you already use a sending platform with built-in warmup? If you send through Instantly or Smartlead, their warmup covers the basics at no extra cost. Only add a standalone tool if you need diagnostics (inbox placement testing, spam-score monitoring) that the bundled tools lack.
How many client inboxes are you warming? At 1 to 3 inboxes, any per-inbox tool works — the absolute cost is under $75/month. At 10+ inboxes, flat-rate tools (Mailivery, TrulyInbox) cost 5 to 10 times less than per-inbox alternatives. A 50-inbox agency on MailReach pays ~$975/month; the same 50 inboxes on Mailivery's Business plan cost $199/month.
Do you need inbox placement testing alongside warmup? If yes, MailReach bundles 20 spam-test credits per month, and Mailivery includes placement testing on every plan. Most standalone per-inbox tools (Warmup Inbox, Warmbox, Mailwarm) do not include testing at all — you would need to add a separate tool like GlockApps at $40 to $100/month.
A properly warmed domain with correct SPF, DKIM, and DMARC authentication hits 87% inbox placement and 4.1% reply rates. The identical email from a brand-new unwarmed domain lands in the inbox just 12% of the time — a 7x gap driven almost entirely by warmup status, per the 2026 Cold Email Benchmark Report. Skip warmup and you are sending spam-folder email with good copy attached.
Read next
- Best Cold Email Tools for Agencies (2026) — the sending layer that warmup feeds into; pairs with this post as the full deliverability stack
- Best Email Verification Tools for Agencies (2026) — the list-cleaning step that runs before warmup; a dirty list sinks even a warmed inbox
- The Best Outbound Tech Stack for Agencies (2026) — how warmup fits into the full outbound stack alongside sending, verification, and CRM
- CloseFast (closefa.st) — the prospect-discovery layer that runs before warmup: find clients whose marketing gaps justify the cold email you are about to warm up for