TL;DR
- Instantly and Smartlead both include unlimited warm-up across unlimited mailboxes on every plan, from $37.60/month and $39/month respectively. Best for: any team whose sending platform is not already fixed, because the marginal cost of warming another inbox is zero.
- Mailreach is the strongest fit where diagnosis matters: per-ESP inbox placement reporting, so you can see that Gmail accepts you while Outlook filters you. Best for: teams troubleshooting a specific placement problem.
- Warmforge is the strongest fit on price-to-quality at $9/month per inbox, warming only against aged Google Workspace and Microsoft 365 accounts. Best for: cost-sensitive teams that care about network composition.
- The category has largely been absorbed into the sending platforms. Paying separately for warm-up in 2026 needs a specific reason, usually reporting depth rather than warm-up itself.
Contents
- How to judge a warm up tool
- The 8 tools compared
- Pricing comparison
- The rules that matter more than the tool
- FAQ
Email warm-up sends and replies to messages between real or network-controlled inboxes to build a positive sending history before you run real campaigns. A new domain sending 50 cold emails on day one will land in spam, and no copy or offer fixes that.
How to judge a warm up tool
Four things matter. Most reviews list features instead.
1. Network quality, not network size. A network of 50,000 disposable inboxes is worse than 5,000 aged, reputable ones. Mailbox providers weight the reputation of the sending and receiving domains, so interactions with throwaway accounts contribute little and can signal manipulation. Warmforge is the only tool here that makes network composition its explicit selling point.
2. Pricing axis. Per-inbox pricing punishes exactly the setup that works. Best practice is 10+ domains and 20+ inboxes. At $69 per inbox per month, that is $1,380/month for warm-up alone. On Instantly or Smartlead it is $0 on top of your sending plan.
3. Reporting depth. Knowing you are warming is not the same as knowing where you land. Per-ESP placement reporting tells you whether the problem is Gmail or Microsoft, and those have different fixes.
4. Whether it survives a platform switch. Lemwarm is tied to Lemlist and is not transferable. Mailreach works with any sequencer via API.
The 8 tools compared
| Tool | Type | Price | Free trial | Standout |
|---|---|---|---|---|
| Instantly | Bundled | Included from $37.60/month | Yes | Unlimited inboxes, large network |
| Smartlead | Bundled | Included from $39/month | Yes | Unlimited inboxes, agency friendly |
| Warmy | Standalone | ~$49 to $279/month | 7 days | Google Postmaster integration |
| Lemwarm | Bundled with Lemlist | Per inbox, requires Lemlist | With Lemlist trial | Mature, well-tuned algorithm |
| Mailreach | Standalone | Per mailbox, 20% annual discount | No | Per-ESP placement reporting |
| Warmforge | Standalone | $9/month per inbox | 1 free slot | Aged Google and Microsoft accounts only |
| Mailivery | Standalone | From ~$22/month | 7 days, card required | Unlimited inboxes on a shared cap |
| Mailwarm | Standalone | $69/month per inbox | No | 50,000+ inbox network |
1. Instantly
Type: Bundled with the sending platform. Best for: Teams running cold email at volume.
Instantly includes unlimited warm-up across unlimited email accounts on every Outreach plan, with pricing scaling on sending volume rather than inbox count. Adding your twenty-first mailbox costs nothing.
The network is one of the largest in the category, drawn from 35,000+ businesses. Warm-up runs alongside inbox placement testing, automatic bounce protection, and sending pattern randomisation in the same platform, so the warm-up schedule and campaign schedule are aware of each other. Standalone tools cannot do that.
Pricing: Growth $37.60/month on annual billing, or $47 monthly. Higher Outreach tiers scale by volume. Warm-up is included at every level.
Where it falls short: You are buying a sending platform. If you are committed to a different sequencer, this is not available to you. The lead database and CRM are separate products.
Verdict: If you are paying separately for warm-up while running Instantly, you are paying twice.
2. Smartlead
Type: Bundled. Best for: Agencies managing many client mailboxes.
Smartlead also includes unlimited mailboxes and unlimited warm-up on every plan, from $39/month for Base with 2,000 active contacts and 6,000 emails/month. Plans are limited by active leads and monthly sends rather than inbox count.
Smartlead's published warm-up guidance is the clearest in the category and worth following whichever tool you use: run at least 10 domains and 20+ inboxes, ramp each inbox from 0 to 30 emails/day, and expect 95 to 97% inbox placement with that configuration.
Where it falls short: SmartInfra, SmartProspect, SmartAgents, and SmartDialer are separate add-ons, so total cost climbs above the headline.
Verdict: Equivalent to Instantly on warm-up economics. Choose between them on the sending platform, not the warm-up.
3. Warmy
Type: Standalone. Best for: Teams wanting warm-up plus diagnostics without switching sequencer.
Warmy connects to Google Postmaster Tools, giving it access to Google's own view of your domain reputation and spam rate rather than an inferred estimate. Since Google's bulk sender requirements are defined against exactly those metrics, that is a direct feedback loop. It supports 30+ languages in warm-up content and works with 35,000+ businesses.
Pricing: Third-party reported figures put Warmy in the range of roughly $49 to $279/month depending on inbox count and features. A 7-day free trial is available, with no permanent free plan. Pricing is not fully transparent on the site, which is a real friction point.
Where it falls short: Per-inbox pricing at scale, and the pricing opacity. At 20 inboxes you pay materially more than a full Instantly subscription that includes warm-up plus a sending platform.
Verdict: The strongest standalone option if you must stay on your current sequencer.
4. Lemwarm
Type: Bundled with Lemlist. Best for: Teams already on Lemlist.
Lemwarm was one of the first warm-up products in the category and has had the longest time to tune its behaviour. It ramps gradually, varies content, and mirrors real conversation patterns well.
Pricing: Per inbox, requiring a Lemlist subscription. Lemlist's Email plan is $69/month, or $55 on annual billing, priced per workspace with unlimited users.
Where it falls short: Not transferable. Lemwarm only warms inboxes you send from through Lemlist, so leaving means abandoning the warm-up history you built.
Verdict: Excellent if you are on Lemlist. Not a reason to move to Lemlist.
5. Mailreach
Type: Standalone. Best for: Diagnosing which mailbox provider is filtering you.
Mailreach's differentiator is reporting granularity. It reports inbox placement per ESP, so you can see Gmail accepting you while Outlook routes you to junk. Most tools report a single aggregate figure, which is close to useless for diagnosis, because the fix for a Microsoft problem differs from a Gmail one. It works with any sequencer through its API.
Pricing: Per mailbox, with only a 20% discount on annual billing, below the category norm. No free trial.
Where it falls short: Cost at scale, no free trial, and reported interface slowdown once you manage 30+ inboxes.
Verdict: Buy it as a diagnostic for a month when something breaks, rather than as a permanent line item.
6. Warmforge
Type: Standalone. Best for: Cost-sensitive teams that care about network quality.
Warmforge is $9/month per inbox, or free if you use Salesforge as your sending platform. It gives one free warm-up slot and one free inbox placement test per month, so you can validate it before paying.
The substantive claim is network composition. Warmforge warms only against aged Google Workspace and Microsoft 365 accounts rather than a mixed pool. Since providers weight the reputation of interacting domains, a smaller high-quality network is a defensible design choice.
Where it falls short: Smaller network, less mature reporting than Mailreach or Warmy, and a shorter track record.
Verdict: The best price-to-quality ratio among standalone tools, and the strongest argument that network size is the wrong metric.
7. Mailivery
Type: Standalone. Best for: Teams warming a small number of mailboxes on a tight budget.
Mailivery's Starter plan is around $22/month and allows unlimited inboxes, but with a shared cap of 200 warm-up emails per day across all of them. That detail decides whether it works for you. Twenty inboxes sharing 200 daily emails means 10 each, a slow ramp. Five inboxes means 40 each, a healthy pace.
Pricing: From roughly $22/month. A 7-day trial is available but requires a credit card.
Where it falls short: The shared daily cap, and the card requirement on the trial.
Verdict: Good value under 10 inboxes. Misleading value above 20.
8. Mailwarm
Type: Standalone. Best for: Teams with very few inboxes and no price sensitivity.
Mailwarm operates a network of 50,000+ inboxes, the largest claimed figure here.
Pricing: $69/month for a single inbox. Growth $159/month for up to 3. Scale $479/month for up to 10. No free trial.
Where it falls short: The pricing is difficult to defend in 2026. Ten inboxes on Mailwarm costs $479/month. The same ten on Instantly cost $37.60/month with warm-up included, alongside a full sending platform. Network size does not close a gap that large, particularly since composition matters more than count.
Verdict: Included for completeness rather than as a recommendation.
Pricing comparison
| Tool | Price | Pricing axis | Cost at 20 inboxes |
|---|---|---|---|
| Instantly | From $37.60/month | Sending volume | $37.60/month |
| Smartlead | From $39/month | Active leads and sends | $39/month |
| Warmforge | $9/month per inbox | Per inbox | ~$180/month |
| Mailivery | From ~$22/month | Shared 200/day cap | ~$22/month, 10 emails per inbox |
| Warmy | ~$49 to $279/month | Per inbox and features | Upper end of range |
| Mailreach | Per mailbox | Per mailbox | Substantial |
| Mailwarm | $69/month per inbox | Per inbox tiers | Beyond published tiers |
| Lemwarm | Per inbox + Lemlist | Per inbox | Requires Lemlist |
The rules that matter more than the tool
No warm-up tool compensates for a broken setup.
Configure authentication before you warm. SPF, DKIM, and DMARC must be in place. Google and Yahoo require all three from senders of 5,000+ messages/day to Gmail, along with one-click unsubscribe per RFC 8058 and TLS on transmission.
Watch the spam rate ceiling. Google requires your spam complaint rate in Postmaster Tools to stay below 0.10% and explicitly warns senders never to reach 0.30% or higher. Crossing that damages the domain in a way warm-up will not quickly undo.
Warm for three weeks before real sending. Unify considers a mailbox fully warmed after roughly three weeks on an automated schedule. Anything faster is optimistic.
Cap daily volume conservatively. Unify defaults to 25 emails per mailbox per day, configurable to 65 when engagement supports it. Smartlead recommends ramping 0 to 30 per day. Spread volume across 10+ domains and 20+ inboxes rather than pushing any single mailbox harder.
Keep warming during campaigns. Stopping after launch lets the positive signal decay while cold volume increases, which is the worst combination.
Fix your list before blaming your warm-up. A 20% bounce rate destroys sender reputation faster than any warm-up tool rebuilds it. Findymail guarantees a bounce rate under 5% and refunds credits if exceeded, which protects your warm-up investment more effectively than a second warm-up tool would.
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FAQ: Email Warm Up Tools
How long does email warm up take?
Roughly three weeks for a new mailbox on an automated schedule. Unify treats a mailbox as fully warmed after about three weeks, and Smartlead's guidance is to ramp from 0 to 30 emails/day over a comparable period. Warming a domain previously damaged by high bounce or complaint rates takes longer and sometimes does not fully recover.
Is email warm up still necessary in 2026?
Yes, and more than before. Google and Yahoo tightened bulk sender requirements to mandate SPF, DKIM, DMARC, one-click unsubscribe, and TLS for senders of 5,000+ daily messages to Gmail, with a spam complaint rate that must stay below 0.10%. A cold domain sending at volume into that environment will be filtered.
What is the best free email warm up tool?
There is no meaningful permanent free standalone warm-up tool. The closest equivalent is unlimited warm-up bundled with Instantly from $37.60/month or Smartlead from $39/month, which costs less than most single-inbox standalone plans. Warmforge offers one free warm-up slot and one free placement test per month, and is free entirely if you send through Salesforge.
How many emails per day should I send during warm up?
Start at zero and ramp to around 25 to 30 emails per inbox per day over roughly three weeks. Unify caps mailboxes at 25/day by default and allows up to 65 when engagement supports it. Rather than pushing a single inbox harder, add inboxes. Best practice is 10+ domains and 20+ inboxes.
Do I need a separate warm up tool if I use Instantly or Smartlead?
No. Both include unlimited warm-up across unlimited mailboxes on every plan. The only reasons to add a standalone tool are per-ESP inbox placement diagnostics, where Mailreach is strongest, or Google Postmaster integration, where Warmy is. Both are diagnostic purchases rather than permanent ones.
Yananai A. Chiwuta
Author
Yananai Chiwuta is a Go-To-Market Architect and founder of Forma Nôrden. He builds Go-To-Market growth systems for B2B companies selling into enterprise and mid-market accounts.
Celine Sky
Reviewer
Celine ensures technical accuracy and strategic alignment across all Forma Nôrden playbooks and resources.
