Deliverability Report • 2026 Edition

Email Warmup Tools in 2026: 10 Tested for Deliverability

We ran 10 email warmup tools through real cold outreach inboxes and measured network size, deliverability lift, ramp speed, pricing per inbox, and how each one plays with sending platforms. Here is the full breakdown for cold email teams, agencies, and solo founders.

calendar_today Jun 2026

lab_profile 10 Tools Tested

mark_email_read Inbox Placement Tested

schedule 16 min read

lightbulb Key takeaways

arrow_rightIf you already use Instantly or Smartlead for sending, the bundled warmup is the most cost-effective option in 2026. Unlimited inboxes warmed at no extra cost makes standalone tools hard to justify for high-volume teams.
arrow_rightStandalone warmup pricing runs $19 to $359 per inbox per month. Mailwarm and Folderly sit at the premium end. TrulyInbox and Warmup Inbox are the most affordable per-inbox standalone options.
arrow_rightWarmy and Folderly go beyond warmup with full deliverability monitoring, spam placement tests, and DNS health checks. Worth the premium for teams sending 50,000+ emails per month.
arrow_rightLemwarm is the cleanest pick for Lemlist users thanks to the native integration. For everyone else, the smaller network limits how fast reputation builds.
arrow_rightWarmup without verified emails is wasted effort. A clean data layer (Mailsfinder, ZeroBounce, MillionVerifier) keeps bounces low so warmup reputation actually compounds instead of getting torn down by every send.
arrow_rightMailreach and Allegrow are the strongest picks for agencies running 20+ client inboxes with workspace-level reporting.
arrow_rightBrand new domains need 2 to 4 weeks of warmup before any cold outreach. Rushing this step is the single most common reason cold campaigns land in spam.

Jump to a tool

1. Instantly Warmup 2. Smartlead Warmup 3. Mailwarm 4. Warmup Inbox 5. Lemwarm 6. Warmy 7. Mailreach 8. Folderly 9. TrulyInbox 10. Allegrow

How We Tested • Comparison Table • Category Picks • Pricing • FAQ

How we tested these tools

We connected each warmup tool to fresh and aged inboxes across Google Workspace and Microsoft 365, then measured what actually changed in inbox placement, network behaviour, and total cost.

trending_up

Deliverability lift

Change in primary inbox placement after 2 to 4 weeks of warmup activity.

hub

Network size

Total number of warmed inboxes available for engagement, and diversity across providers.

speed

Ramp control

How fast and how granular the ramp schedule is from day one to maintenance volume.

integration_instructions

Platform fit

Native integrations with sending platforms (Instantly, Smartlead, Lemlist, HubSpot, custom SMTP).

payments

Pricing per inbox

True monthly cost per warmed inbox at entry and scale.

monitor_heart

Monitoring depth

Placement tests, DNS health, blacklist checks, and remediation guidance beyond warmup itself.

Master comparison table

#	Tool	Price Starts	Inboxes	Standalone?	API	Best For	Rating
1	Instantly Warmup	Included w/ Instantly	Unlimited	Bundled	check_circle	Cold outreach teams	4.7 (G2) star
2	Smartlead Warmup	Included w/ Smartlead	Unlimited	Bundled	check_circle	Agencies, multi-domain	4.7 (G2) star
3	Mailwarm	$69/mo	1 inbox	Standalone	cancel	High-trust standalone	4.5 (G2) star
4	Warmup Inbox	$19/mo	1 inbox	Standalone	check_circle	Solo founders	4.4 (G2) star
5	Lemwarm	$29/mo	1 inbox	Standalone	check_circle	Lemlist users	4.4 (G2) star
6	Warmy	$59/mo	1 inbox	Standalone	check_circle	ML-driven warmup	4.7 (G2) star
7	Mailreach	$25/inbox/mo	1 inbox	Standalone	check_circle	Per-inbox value	4.6 (G2) star
8	Folderly	$96/inbox/mo	1 inbox	Platform	check_circle	Full deliverability	4.6 (G2) star
9	TrulyInbox	$29/mo	5 inboxes	Standalone	check_circle	Affordable multi-inbox	4.5 (G2) star
10	Allegrow	$87/mo	1 inbox	Platform	check_circle	Enterprise analytics	4.5 (G2) star

database

Warmup is only half the deliverability stack

A warmed inbox builds reputation. A clean list keeps that reputation intact. Every bounce from an invalid email signals to Gmail and Outlook that you are sending blindly, which undoes weeks of warmup work in days. The teams with the highest reply rates run both layers together: verified emails on the data side, plus continuous warmup on the inbox side.

Mailsfinder sits on the data layer. Every email returned goes through dual-layer SMTP verification before it ever touches your sending tool. That means the inbox you warmed yesterday is not getting torched by bounces tomorrow. Pair it with any of the warmup tools below and you have the foundation for sustainable cold outreach. Read more in our guide to setting up cold email infrastructure or check our free email verifier and deliverability checker.

Instantly Warmup

BUNDLED WARMUP + SENDING PLATFORM

For teams already sending through Instantly, the bundled warmup is the strongest argument for staying inside one platform. Unlimited inboxes get warmed at no extra cost, the network is one of the largest in the industry, and the schedule auto-adjusts based on the inbox provider and account age. Conversations include realistic reply patterns and varied content templates, which helps avoid pattern detection by spam filters. The trade-off is that you have to use Instantly as your sending platform, since the warmup is not sold separately.

Key features

check

Unlimited inbox warmup included on every paid plan

check

Large network with diverse Gmail and Outlook inboxes

check

Auto-ramp schedules tied to inbox age and provider

check

Native integration with Instantly campaigns and analytics

Pros

check_circleBest cost per inbox for high-volume teams
check_circleAuto-pause when inbox sends campaigns
check_circleSolid 4.7 G2 rating from active users

Cons

cancelOnly works inside Instantly sending platform
cancelNo granular content control per conversation
cancelLess detailed placement reporting than Folderly

"We run 40 inboxes inside Instantly and warmup costs us nothing extra. Inbox placement holds steady even during heavy campaign weeks."
-- Cold Email Agency Owner via G2

Included with Instantly plans Unlimited inboxes

Smartlead Warmup

BUNDLED WARMUP + AGENCY-FOCUSED PLATFORM

Agencies running multiple client domains tend to gravitate to Smartlead, and the bundled warmup is a big reason why. Every inbox connected to Smartlead can be warmed in parallel with no per-inbox fee, and the AI behind it varies subject lines, body content, and reply timing to mimic genuine conversation. Workspace-level reporting helps agencies show clients exactly how reputation is trending without exposing raw inbox data. The warmup feels less polished than Instantly's interface, but the underlying network and AI control are very similar.

Key features

check

Unlimited warmup across all connected inboxes

check

AI varies content and reply patterns by conversation

check

Workspace-level reporting for multi-client agencies

check

API access for custom integrations and reporting

Pros

check_circleStrong agency tooling and white-label options
check_circleUnlimited inboxes warmed at base plan price
check_circle4.7 G2 rating with active community feedback

Cons

cancelWarmup UI feels less polished than Instantly
cancelRequires Smartlead as the sending platform
cancelOnboarding curve for non-technical teams

"Running 12 clients on Smartlead with unlimited warmup. Reply rates held above 8% all quarter thanks to consistent inbox placement."
-- Agency Founder via G2

Included with Smartlead plans Unlimited inboxes

Mailwarm

STANDALONE WARMUP

One of the first names in dedicated warmup, Mailwarm operates a network of 100,000+ real inboxes that engage with your messages every day. Pricing starts at $69 per month per inbox with higher tiers at $179 per month for accelerated schedules. The network size is the real selling point: when your warmup conversations are happening with that many other inboxes, the engagement looks unmistakably real to spam filters. The downside is the per-inbox pricing, which gets expensive fast if you run more than 3 or 4 sending accounts.

Key features

check

100,000+ inbox network for engagement diversity

check

Automated reply, open, and mark-as-important signals

check

Multiple tiers for slow versus accelerated ramps

check

Works with any sending platform via SMTP credentials

Pros

check_circleLargest claimed warmup network in this list
check_circleWorks with any sending tool, no lock-in
check_circleProven track record since 2019

Cons

cancelExpensive per-inbox at $69 to $179 monthly
cancelNo public API for custom workflows
cancelInterface looks dated compared to newer tools

"We used Mailwarm to rescue a domain that landed in spam. Three weeks of consistent warmup brought inbox placement back to 88%."
-- SaaS Founder via G2

From $69/mo per inbox 100K+ network

Warmup Inbox

AFFORDABLE STANDALONE WARMUP

Founded by a team that previously built cold outreach tools, Warmup Inbox sits at the lower end of the price band starting at $19 per month per inbox. The setup is genuinely beginner-friendly: connect via OAuth, pick a ramp schedule, done. Tiers go up to $249 per month for larger volumes and custom configurations. Solo founders and small teams pick this when they want a working warmup tool without committing to a full sending platform. The network is smaller than Mailwarm or Instantly, so reputation building takes a bit longer, but it still gets the job done for typical cold outreach volumes.

Key features

check

OAuth setup in under 5 minutes

check

Free trial and 7-day money-back guarantee

check

Deliverability dashboard with placement scoring

check

Works alongside any sending platform

Pros

check_circleLowest entry price in standalone warmup
check_circleClean dashboard suited to non-technical users
check_circleSolid 4.4 G2 rating with consistent feedback

Cons

cancelSmaller network slows down ramp speed
cancelLimited reporting compared to Folderly
cancelPer-inbox pricing scales linearly

"Cheap, simple, works. I run 3 inboxes on Warmup Inbox and have zero spam complaints across 6 months of cold outreach."
-- Solo Founder via G2

From $19/mo Up to $249/mo

Lemwarm

WARMUP BY THE LEMLIST TEAM

Built by the Lemlist team, Lemwarm naturally fits sales teams already running their cold outreach through Lemlist's sequences. Pricing starts at $29 per inbox per month, and there is a free tier for very small teams that want to test before committing. The product is solid and the team behind it is one of the most active voices in cold outreach education, which means you also get a lot of free content on deliverability best practices alongside the tool itself. The catch is that the network is smaller than Mailwarm or Instantly, which can extend the time it takes to fully warm a new inbox.

Key features

check

Free tier for small teams testing warmup

check

Native integration with Lemlist campaigns

check

Auto-pause when campaigns send at high volume

check

Strong educational content and active community

Pros

check_circleFree tier removes risk for small teams
check_circleTight integration with Lemlist sending workflow
check_circleTrusted brand with deep cold email pedigree

Cons

cancelSmaller network than Instantly or Mailwarm
cancelMost useful for teams already on Lemlist
cancelReporting depth lighter than Folderly or Warmy

"Lemwarm pairs naturally with our Lemlist campaigns. The auto-pause feature alone saves us from triggering daily sending caps."
-- Sales Ops Lead via G2

From $29/inbox/mo Free tier available

Warmy

ML-DRIVEN WARMUP + DELIVERABILITY

Warmy markets itself on the strength of its machine learning engine that adapts ramp schedules based on real-time inbox placement signals. Pricing starts at $59 per month per inbox and runs up to $359 per month for the enterprise tier with advanced placement diagnostics. The product blends warmup with deliverability monitoring (placement tests across Gmail, Outlook, and Yahoo) and DNS health checks. Heavy senders who want one tool that handles both layers tend to prefer it over Mailwarm or Mailreach. The trade-off is the price tag, which is significantly higher than entry-level standalone tools.

Key features

check

ML-driven ramp schedule adapts to live placement data

check

Inbox placement tests across major providers

check

DNS health checks for SPF, DKIM, DMARC

check

Templates library with industry-tuned conversations

Pros

check_circleCombines warmup and monitoring in one platform
check_circleAdaptive ramp schedules cut over-sending risk
check_circle4.7 G2 rating reflects strong user satisfaction

Cons

cancelPremium pricing starting at $59 per inbox
cancelEnterprise tier needed for full diagnostics
cancelSteeper learning curve than entry-level tools

"Warmy gave us a complete deliverability picture in one dashboard. The adaptive ramp prevented us from over-sending after a domain reset."
-- Head of Outbound via G2

From $59/inbox/mo Up to $359/mo enterprise

Mailreach

PER-INBOX STANDALONE WARMUP

Mailreach hits the sweet spot between Mailwarm's network strength and Warmup Inbox's pricing model. At $25 per inbox per month (with discounts up to $99 per inbox for higher-volume tiers), it stays affordable even for teams running 5 to 10 sending accounts. The platform also includes a spam test suite that shows where your messages are landing in Gmail, Outlook, Apple Mail, and Yahoo before you scale a campaign. The interface is clean, the documentation is thorough, and the warmup engine has been in the market long enough to have a track record agencies trust.

Key features

check

Spam test suite for Gmail, Outlook, Apple, Yahoo

check

Granular ramp settings with daily volume control

check

Workspace-level reporting for agency clients

check

API access for automation and reporting

Pros

check_circleSolid balance of price and feature depth
check_circleBuilt-in spam test is genuinely useful
check_circle4.6 G2 rating with detailed agency reviews

Cons

cancelPer-inbox pricing adds up beyond 10 accounts
cancelNo bundled sending platform for end-to-end use
cancelSpam test counts use a separate credit pool

"Mailreach is the warmup we recommend to every new client who is not already on Instantly or Smartlead. Reliable and easy to onboard."
-- Outbound Consultant via G2

From $25/inbox/mo Up to $99/inbox/mo

Folderly

DELIVERABILITY PLATFORM WITH WARMUP

Folderly positions itself less as a warmup tool and more as a full deliverability platform. Starting at $96 per inbox per month, it includes ongoing warmup, blacklist monitoring, content analysis, DNS configuration help, and weekly placement reports. The team behind it is hands-on with customers, especially on enterprise plans where a dedicated specialist will diagnose and remediate deliverability problems. For teams sending high volume where a single deliverability incident costs significant revenue, the price tag makes sense. For smaller teams or solo founders, the cost is hard to justify against simpler standalone tools.

Key features

check

Full deliverability platform with active warmup

check

Blacklist monitoring and removal assistance

check

Content analysis flags spam-trigger phrasing

check

Hands-on specialist support on enterprise tiers

Pros

check_circleMost comprehensive deliverability coverage
check_circleHuman specialists assist with remediation
check_circle4.6 G2 rating with enterprise testimonials

Cons

cancelPremium price point at $96+ per inbox monthly
cancelOverkill for low-volume cold outreach teams
cancelLong onboarding compared to plug-and-play tools

"Folderly pulled our domain out of a Microsoft blacklist within 10 days. The specialist support is worth every dollar at our send volume."
-- Enterprise Sales Director via G2

From $96/inbox/mo Specialist support included

TrulyInbox

AFFORDABLE MULTI-INBOX WARMUP

Among the standalone tools, TrulyInbox stands out for letting you warm multiple inboxes on a single subscription. Starting at $29 per month, the entry plan covers up to 5 inboxes, with the top tier at $99 per month supporting 25 inboxes. For teams that need standalone warmup but do not want to pay per inbox, this is one of the few options on the market. The warmup engine itself is straightforward, the dashboard shows daily progress per inbox, and pricing stays predictable as you scale. The trade-off is a smaller network than premium tools, which extends the ramp window slightly.

Key features

check

Up to 25 inboxes on a single subscription

check

Per-inbox progress tracking in the dashboard

check

Daily volume control and ramp customization

check

Works alongside Instantly, Smartlead, or HubSpot

Pros

check_circleMulti-inbox value beats per-seat pricing models
check_circlePredictable monthly cost as inboxes grow
check_circle4.5 G2 rating with consistent practitioner feedback

Cons

cancelSmaller engagement network than Mailwarm
cancelReporting is basic compared to Folderly
cancelLimited native integrations beyond major platforms

"We run 18 inboxes on TrulyInbox for less than two seats of Mailreach. The math just works for our agency."
-- Agency Operator via G2

From $29/mo (5 inboxes) Up to $99/mo (25 inboxes)

Allegrow

ENTERPRISE WARMUP + ANALYTICS

Allegrow targets the enterprise end of the warmup market with prices starting at $87 per month and reaching $149 per month for advanced analytics tiers. The platform layers warmup on top of detailed reporting on sender reputation, inbox placement, and engagement metrics. Sales operations teams running tools like Outreach or Salesloft pick Allegrow because it integrates cleanly into existing stacks without forcing a switch to a new sending platform. The interface is geared toward analysts, not solo founders, which is both its strength and its limitation depending on the team using it.

Key features

check

Detailed sender reputation analytics dashboards

check

Inbox placement scoring across major providers

check

Integrates with Outreach, Salesloft, HubSpot

check

Custom reporting for sales operations teams

Pros

check_circleStrong analytics for sales ops teams
check_circleIntegrates with enterprise sales platforms
check_circle4.5 G2 rating from enterprise reviewers

Cons

cancelPricing aimed at enterprise, not startups
cancelInterface assumes analyst-level fluency
cancelOnboarding is heavier than plug-and-play tools

"Allegrow gave our RevOps team the reputation analytics we needed to defend cold outreach as a channel internally. The integrations are clean."
-- RevOps Manager via G2

From $87/mo Up to $149/mo advanced

The category picks

rocket_launch

Best for cold outreach teams

Bundled warmup with unlimited inboxes inside a full sending platform.

Our pick Instantly Warmup

Also strong Smartlead Warmup

savings

Best budget standalone

Low entry price for solo founders running 1 to 3 sending inboxes.

Our pick Warmup Inbox

Also strong TrulyInbox

monitor_heart

Best for full deliverability

Warmup plus placement tests, DNS health, and remediation support.

Our pick Folderly

Also strong Warmy

group

Best for agencies

Multi-client workspaces with per-inbox reporting and reasonable pricing.

Our pick Mailreach

Also strong Smartlead Warmup

smart_toy

Best ML-driven warmup

Adaptive ramp schedules that respond to live placement data.

Our pick Warmy

Also strong Allegrow

handshake

Best for Lemlist users

Tight native integration with Lemlist sequences and education content.

Our pick Lemwarm

Also strong Mailreach

Pricing breakdown: what you actually pay

Side-by-side cost of warmup at entry pricing, scaled across the 10 tools.

Tool	Free Trial	Entry Price	Inboxes	Cost/Inbox	Model
Instantly Warmup	14-day trial	$37/mo (Instantly)	Unlimited	Effectively $0	Bundled
Smartlead Warmup	14-day trial	$39/mo (Smartlead)	Unlimited	Effectively $0	Bundled
Mailwarm	7-day	$69/mo	1	$69	Per-inbox
Warmup Inbox	7-day	$19/mo	1	$19	Per-inbox
Lemwarm	Free tier	$29/mo	1	$29	Per-inbox
Warmy	7-day trial	$59/mo	1	$59	Per-inbox
Mailreach	7-day trial	$25/inbox/mo	1	$25	Per-inbox
Folderly	Demo only	$96/inbox/mo	1	$96	Per-inbox platform
TrulyInbox	7-day trial	$29/mo	5	$5.80	Multi-inbox tier
Allegrow	Demo only	$87/mo	1	$87	Per-inbox platform

* Pricing reflects entry tiers as of June 2026. Volume and annual discounts available from most vendors. Verify current pricing on each tool's website before purchasing.

info

Note: Bundled warmup (Instantly, Smartlead) is effectively free per inbox once you commit to the sending platform. Standalone tools make sense for teams that want platform independence or already use HubSpot, Outreach, or Salesloft for sending. Read more in our guide to the best cold email software and the best email deliverability tools.

Frequently asked questions

What is email warmup and why does it matter for cold outreach? expand_more

Email warmup is the process of gradually increasing the sending volume of a new or dormant inbox while triggering positive engagement signals (opens, replies, marks as important). Inbox providers like Gmail and Outlook use sender reputation to decide whether your messages reach the primary inbox, the promotions tab, or spam. A warmup tool simulates real conversations between your inbox and a network of other warmed inboxes, slowly building reputation. Without warmup, even a perfectly written cold email can land in spam from day one. Tools like Instantly Warmup, Smartlead, and Mailwarm automate this by sending and replying to small batches of emails daily until your inbox is trusted.

How long does it take to warm up an email account? expand_more

Most warmup tools recommend 2 to 4 weeks for a brand new inbox before sending any cold outreach. The exact timeline depends on the domain age, the sending provider (Google Workspace vs. Microsoft 365 vs. custom SMTP), and the volume you plan to send. Tools like Warmup Inbox and Mailreach gradually ramp from 2 to 5 emails per day in week one to 30 to 40 per day by week four. If you skip the warmup phase or rush it, you risk landing in spam folders and damaging the domain reputation, which is much harder to repair than to build properly the first time.

Are email warmup tools still effective in 2026? expand_more

Yes, but the bar is higher than it used to be. Google and Microsoft have both updated their spam algorithms to detect artificial engagement patterns, so warmup networks have had to evolve. The strongest tools in 2026 (Smartlead Warmup, Instantly, Warmy, Mailreach) now use AI to vary content, timing, and reply patterns so the conversations look authentic. Warmup alone is not enough either. You also need proper SPF, DKIM, DMARC records, a clean sending list (no bounces), and reasonable sending volumes. Skip any of those and even the best warmup tool cannot keep you out of spam.

Do I need a separate warmup tool if my sending platform includes one? expand_more

It depends on the platform. Instantly and Smartlead include warmup as part of their core plans with unlimited inboxes, which makes a separate tool unnecessary for most teams using those platforms. If you send through HubSpot, Outreach, Salesloft, or directly through Gmail/Outlook without an outbound platform, you almost certainly need a standalone warmup tool. Mailwarm, Warmup Inbox, Mailreach, and TrulyInbox are designed for exactly this case. Folderly and Warmy take it a step further by combining warmup with broader deliverability monitoring and remediation.

How much does email warmup actually cost in 2026? expand_more

Standalone warmup tools range from $19 per month (Warmup Inbox starter) to $359 per month (Warmy enterprise) per inbox. The cheapest unlimited option is bundled inside Instantly and Smartlead, where warmup is included on plans starting around $37 to $39 per month for unlimited inboxes. Per-inbox pricing varies widely: Mailreach is $25 per inbox per month, Mailwarm starts at $69 per inbox per month, and Folderly enterprise warmup costs $96+ per inbox per month. For most cold outreach teams sending from 5 to 20 inboxes, using a bundled platform like Instantly or Smartlead saves significant money versus paying per inbox.

Does email warmup work if my list has bad data? expand_more

No, and this is the most underestimated factor in deliverability. Warmup builds a positive reputation, but every hard bounce from an invalid email tears that reputation down faster than warmup can build it. The order matters: verify your list first, then warm up, then send. Tools like Mailsfinder, ZeroBounce, and MillionVerifier remove invalid addresses before they hit your inbox. Sending to a warmed inbox with a clean list is what actually keeps you in the primary inbox. Sending to a warmed inbox with a dirty list still gets you flagged within days. Treat verification and warmup as two halves of the same deliverability stack, not optional steps.

What is the difference between warmup and deliverability monitoring? expand_more

Warmup actively builds reputation by simulating engagement. Deliverability monitoring measures where your real emails are landing (primary inbox, promotions, spam) and alerts you when placement drops. Tools like Folderly, Warmy, and Allegrow combine both. They run warmup conversations in the background and continuously test placement across major providers. Standalone tools like Mailreach focus mainly on warmup, while platforms like GlockApps focus only on monitoring. For high-volume senders, having both layers is worth the cost because it lets you catch a deliverability drop within hours rather than after a full campaign tanks.

Can I use multiple warmup tools on the same inbox at once? expand_more

Technically yes, but it is rarely a good idea. Running two warmup tools on the same inbox doubles the artificial engagement, which can look unnatural to spam filters and trigger detection algorithms. It also burns through your daily sending caps from the email provider, leaving less room for actual outreach. The cleaner approach is to pick one tool, run it consistently for 2 to 4 weeks, then leave it on at a maintenance volume (10 to 15 emails per day) while you scale outreach. Switching tools mid-warmup is fine, but stacking them is generally counterproductive.

Is Lemwarm still worth using in 2026? expand_more

Lemwarm remains a solid option, especially for teams already using Lemlist for outreach. Pricing starts at $29 per inbox per month, with a free tier for small teams. The strength is the integration with Lemlist's sending platform, so warmup pauses automatically when an inbox is sending cold campaigns at high volume. The trade-off is the network. Lemwarm uses a smaller pool of warmed inboxes than Instantly or Smartlead, which can slow down reputation building if you need to scale fast. For Lemlist users, it is the path of least resistance. For everyone else, the bundled options inside Instantly or Smartlead are usually a better fit.

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