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Best email warmup tools (2026): what we use, and what warmup cannot fix

Email warmup builds a new mailbox's sending reputation by gradually increasing volume and generating positive engagement before you send cold email at full speed. It helps new domains and mailboxes get started, but it does not fix bad lists, broken DNS, or copy that people mark as spam.

Below is the setup OneGTM uses for client sending, then the other warmup and deliverability tools worth knowing, with what each costs. We have no reseller deals with anyone listed.

By Garrett Wolfe, founder of OneGTM (Clay Artisan Solutions Partner) and former GTM engineer at Unify. Updated .

Key takeaways

  • Most cold email platforms now include warmup, so a separate tool is often unnecessary.
  • Our setup is ScaledMail inboxes warmed and sent through Instantly, with SPF, DKIM, and DMARC checked first.
  • Plan on about two weeks of warmup before new mailboxes send at volume, and keep volume per mailbox low.
  • Warmup cannot save a bad list. Verified emails and relevant copy matter more.

The warmup setup OneGTM uses

We separate infrastructure from sending. ScaledMail provides the mailboxes and domain setup, and Instantly warms them and runs the campaigns. We check every domain with our free deliverability checker before it sends.

Instantly

OneGTM uses this

Cold email platform with unlimited connected mailboxes and unlimited warmup through its shared warmup pool on every plan. Paid premium pools of aged Google and Microsoft accounts are available.

Best for: Warmup and sending in one tool

Pricing: Outreach from $47/month, warmup included. Premium warmup pools from $500/month per workspace.

ScaledMail

OneGTM uses this

Sets up and manages pre-configured Google Workspace, Microsoft 365, and SMTP inboxes for cold email, including domains and SPF, DKIM, and DMARC records. It does not warm mailboxes itself, so we pair it with Instantly.

Best for: Mailbox and domain infrastructure at scale

Pricing: Google Workspace $3.50 per mailbox per month; Microsoft $50 per domain per month for 25 mailboxes.

Other email warmup and deliverability tools

Sequencers with built-in warmup come first, then standalone warmup tools, then deliverability and infrastructure products that pair with them.

Smartlead

Cold email platform with unlimited mailboxes, automatic inbox rotation, and unlimited warmup on every plan.

Best for: Agencies and teams sending from many mailboxes

Pricing: Base $39/month; free trial.

lemlist (lemwarm)

lemwarm is lemlist's warmup feature. It is no longer sold on its own and comes with every lemlist plan.

Best for: Teams already using lemlist for multichannel outreach

Pricing: lemlist Email plan $69/month; 14-day free trial.

Apollo

Apollo's deliverability suite includes mailbox warmup on paid plans, alongside its database and sequencer.

Best for: Teams already sending from Apollo

Pricing: Included from the Basic plan, $49/seat/month billed annually.

Woodpecker

Cold email sequencer that includes free warm-up for a set number of mailboxes on each plan.

Best for: Small teams sending personalized sequences

Pricing: Usage-based on contacted prospects; check current pricing. 14-day trial.

MailReach

Standalone warmup through a network of high-reputation accounts, plus inbox placement (spam) tests.

Best for: Warming specific mailboxes and testing placement

Pricing: $19.50 per mailbox per month.

Warmy.io

Automated warmup with deliverability extras such as seed-list tests, DMARC monitoring, and email verification.

Best for: Teams that want warmup and monitoring together

Pricing: From $49/month; 7-day free trial.

Warmbox

Warmup by exchanging emails across a network that spans 11+ providers, including SMTP services like SendGrid and Amazon SES.

Best for: Warming non-Google and non-Microsoft senders

Pricing: Solo $19/month for one inbox.

Mailwarm

Warmup through a network of aged inboxes, with spam score monitoring and calls with a deliverability expert on every plan.

Best for: Teams that want hands-on deliverability help

Pricing: Starter $69/month billed annually for one mailbox.

EmailBison

Cold email platform on single-tenant infrastructure with dedicated IPs and warmup built in, so other customers cannot affect your reputation.

Best for: High-volume senders who want isolated infrastructure

Pricing: $599/month for 500,000 emails a month.

Folderly

Deliverability platform that finds and fixes technical and content problems hurting inbox placement, then monitors delivery.

Best for: Diagnosing an existing deliverability problem

Pricing: $96 per mailbox per month billed yearly; free placement tests and alerts.

Maildoso

SMTP mailboxes built for outbound with IP rotation. Warmup is not included, so it pairs with a tool like Instantly.

Best for: Low-cost outbound mailboxes

Pricing: $75/month for 30 mailboxes.

Prices are from each vendor's site as of October 2026 and change often, so check before you buy. This is an opinionated list, not a paid ranking.

Email warmup tools compared

ToolBest forStarting price
Instantly (OneGTM uses)Warmup and sending in one toolOutreach from $47/month, warmup included
ScaledMail (OneGTM uses)Mailbox and domain infrastructure at scaleGoogle Workspace $3.50 per mailbox per month
SmartleadAgencies and teams sending from many mailboxesBase $39/month
lemlist (lemwarm)Teams already using lemlist for multichannel outreachlemlist Email plan $69/month
ApolloTeams already sending from ApolloIncluded from the Basic plan, $49/seat/month billed annually
WoodpeckerSmall teams sending personalized sequencesUsage-based on contacted prospects
MailReachWarming specific mailboxes and testing placement$19.50 per mailbox per month
Warmy.ioTeams that want warmup and monitoring togetherFrom $49/month
WarmboxWarming non-Google and non-Microsoft sendersSolo $19/month for one inbox
MailwarmTeams that want hands-on deliverability helpStarter $69/month billed annually for one mailbox
EmailBisonHigh-volume senders who want isolated infrastructure$599/month for 500,000 emails a month
FolderlyDiagnosing an existing deliverability problem$96 per mailbox per month billed yearly
MaildosoLow-cost outbound mailboxes$75/month for 30 mailboxes

Starting prices as published by each vendor in October 2026.

What email warmup does and does not do

Warmup tools send and reply to emails between mailboxes in a network, open them, and pull them out of spam, so a new mailbox builds a history of normal, positive activity. That gives mailbox providers a reason to trust it when real campaigns start.

It does not replace the basics. You still need correct SPF, DKIM, and DMARC records, verified email addresses, a low bounce rate, and copy people actually want to answer. Neither Google nor Microsoft has published guidance endorsing warmup networks, so treat warmup as a ramp, not a shield.

How we warm new mailboxes

  • Send from secondary domains, never your main company domain.
  • Set up SPF, DKIM, and DMARC on day one, and test them with the deliverability checker.
  • Warm each mailbox for about two weeks before campaigns start, and keep warmup running afterward at a lower level.
  • Keep daily cold volume per mailbox low and add mailboxes to grow volume instead of pushing each one harder.
  • Verify every address before sending and watch inbox placement, not just open rates.

When it makes sense to get help with cold email infrastructure

Warmup is the easy part. The mistakes that hurt are made earlier and later: sending from the main domain, missing DMARC, too many emails per mailbox, unverified lists, and no one watching placement until meetings dry up.

OneGTM sets up the domains, mailboxes, authentication, and warmup, then runs campaigns with volume and list quality kept inside safe limits. You own every domain and mailbox.

  • You are launching cold email for the first time and want it right on day one.
  • Open or reply rates fell suddenly and you suspect spam placement.
  • You need to scale from a few mailboxes to dozens without burning domains.
  • Your main company domain is already showing up in spam.

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Email warmup tools FAQ

What is the best email warmup tool?
For most cold email teams the best option is the warmup built into their sending platform, such as Instantly or Smartlead, because it is included and runs alongside campaigns. OneGTM warms ScaledMail inboxes through Instantly. Standalone tools like MailReach, Warmy, and Warmbox make sense when you need to warm mailboxes outside a sequencer.
How long should I warm up a new email account?
Plan on about two weeks of warmup before sending cold email at volume from a new mailbox, then keep a lower level of warmup running. New domains and Microsoft mailboxes can take longer.
Is email warmup still necessary?
For new mailboxes and domains, yes. Warmup builds the sending history that providers look for. It will not fix a bad list, missing authentication records, or spammy copy, so it works best alongside verified data and good DNS setup.
Do I need a separate warmup tool if I use Instantly or Smartlead?
Usually not. Both include unlimited warmup on their plans. A separate tool is useful for mailboxes you send from elsewhere or when you want extra placement testing.
Is ScaledMail a warmup tool?
No. ScaledMail provides pre-configured Google Workspace, Microsoft 365, and SMTP inboxes with domain and DNS setup. You still warm those inboxes in a sending platform such as Instantly.
Does warmup prevent emails from going to spam?
It lowers the risk for new mailboxes but does not guarantee inbox placement. Authentication, list quality, bounce rate, sending volume, and how recipients react to your emails all matter more over time.
Should I hire someone to set up cold email infrastructure?
If you are sending low volume from a handful of mailboxes, you can set it up yourself with a sequencer that includes warmup. It is worth getting help when you need dozens of mailboxes, when deliverability has already dropped, or when a mistake on your main domain would be costly.

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