An email warmup tool sends and answers emails between your new mailbox and a network of other mailboxes, so the mailbox builds a sending history before you use it for cold email. If you already send from Instantly, Smartlead, lemlist or Apollo, warmup is part of your plan and you probably do not need another tool. Standalone tools such as Warmup Inbox, MailReach and Warmbox charge per inbox, from about $15 a month.
Every price below was checked on the vendor’s own pricing page on 30 October 2026. Most “best warmup tools” lists are written by companies that sell one, and none of the top results we read explained the Gmail and Yahoo sender rules that decide whether your email reaches the inbox. This page covers both. For the basics of the practice, see our glossary entry on email warm-up.
Which email warmup tools are worth comparing?
| Tool | Type | Price (as listed on 30 October 2026) | What you get | Best for |
|---|---|---|---|---|
| Instantly | Cold email platform | Growth $47 a month, or $37.60 a month billed yearly | ”Unlimited Email Warmup” and unlimited email accounts on every Outreach plan | Teams sending from many mailboxes |
| Smartlead | Cold email platform | Base $39 a month, or $32 billed yearly | Unlimited email accounts; the plan cards show a $59 a month add-on tier on Base and a free “Premium” tier on Unlimited Smart ($174 a month) | Agencies and high volume |
| lemlist (lemwarm) | Cold email platform | Email plan $55 a month billed yearly | lemlist’s FAQ says lemwarm is “included in all plans” | Multichannel sequences |
| Apollo | Data and sequencing platform | Basic $49 per seat a month billed annually, $65 monthly | ”Deliverability Suite & Email Warmup” on paid plans | Teams that also need contact data |
| Warmup Inbox | Standalone warmup | Basic $15 per inbox a month billed annually; Pro $49; Max $79 | 75, 250 or 1,000 warmup messages a day per inbox; 7-day trial; a $0 Freemium plan | Warming inboxes that send from another tool |
| MailReach | Standalone warmup and spam testing | $19.5 per mailbox a month | Warmup up to 100 emails a day, at least 20 spam test credits, health checks for blacklists, SPF, DKIM and DMARC | Teams that want placement tests too |
| Warmbox | Standalone warmup | Solo, 1 inbox: $15 or $19 a month depending on billing; Start-up, 3 inboxes: $69 or $79; Growth, 6 inboxes: $139 or $159 | 50, 250 or 500 warmup emails a day | Small teams with a few inboxes |
Notes on the prices: Warmbox’s page shows two prices per plan behind a yearly and monthly toggle without labeling them clearly, so check at checkout. Smartlead’s plan cards do not say in words which warmup tier each plan includes; confirm before you buy. Instantly and Smartlead price per workspace, not per inbox; our Instantly pricing guide adds up its Outreach, credits and mailbox costs for a small team. Apollo prices per seat. If you are weighing Apollo as your whole stack, our Apollo pricing guide covers its plans and credits.
Do you need a separate warmup tool?
Usually not. The decision comes down to where you send from.
- You send from Instantly, Smartlead, lemlist or Apollo. Warmup is included. Paying for a second warmup network on the same mailboxes adds cost without a clear benefit.
- You send from a tool without warmup, such as your CRM’s sequences, or straight from Google Workspace or Microsoft 365. A standalone tool is the way to warm those mailboxes.
- You want inbox placement tests. MailReach sells warmup and spam tests together. Placement tests tell you where a real campaign email lands, which a warmup score does not.
Illustrative. A team sending cold email from 10 mailboxes on secondary domains would pay $150 a month for Warmup Inbox Basic on annual billing (10 x $15, before any volume discount) or $195 a month for MailReach (10 x $19.5). Instantly’s Growth plan, at $47 a month, includes warmup for unlimited email accounts plus the sending itself. The standalone tool only makes sense if you are not sending from a platform that already warms.
What can warmup not fix?
Warmup builds a history for a mailbox. It does not change the rules mailbox providers apply to every sender. Google has applied its current sender requirements since February 2024, and Yahoo publishes the same core rules.
Google’s email sender guidelines, for everyone sending to personal Gmail accounts:
- Set up SPF or DKIM for your sending domain.
- Have valid forward and reverse DNS records for sending domains or IPs.
- Use a TLS connection.
- Keep the spam rate reported in Postmaster Tools below 0.3%.
For senders of more than 5,000 messages a day to Gmail, Google adds SPF and DKIM, a DMARC record (the policy can be “none”), alignment of the From domain with the SPF or DKIM domain, and one-click unsubscribe for marketing and subscribed messages. Google recommends keeping the spam rate below 0.10% and avoiding 0.30% or higher.
Yahoo’s sender best practices set the same floor: SPF or DKIM at a minimum for all senders, a spam rate below 0.3%, and valid forward and reverse DNS. Bulk senders need SPF and DKIM, a DMARC policy of at least p=none that passes, From-domain alignment, a one-click list-unsubscribe header, and to “honor unsubscribes within 2 days.”
What that means for cold email:
| Problem | Does warmup fix it? | What fixes it |
|---|---|---|
| SPF, DKIM or DMARC missing or failing | No | Set up the records on every sending domain. See SPF, DKIM and DMARC |
| Spam complaints above 0.3% | No | Narrower lists, a relevant reason to write, an easy opt-out |
| High bounce rate | No | Verify addresses before sending; see email bounce rate |
| A new mailbox with no history | Partly | Warmup plus a slow ramp of real sends |
| Emails nobody wants | No | Better targeting and copy |
The spam threshold is the one that catches cold email teams. A warmup network can produce opens and replies, but it cannot stop real recipients from marking your email as spam. Watch the Gmail spam rate in Google Postmaster Tools for each sending domain.
How do you set up warmup properly?
- Use secondary domains. Do not send cold email from your main company domain. Our glossary entry on domain warmup covers the setup.
- Authenticate first. SPF, DKIM and DMARC on every sending domain, checked before warmup starts.
- Start warmup before any campaign, and keep campaign volume low per mailbox for the first weeks.
- Verify your list. Bounces hurt your sender reputation whatever the warmup tool reports.
- Write email people want. Short, specific and sent to the right person. Our cold email templates and cold email subject lines guide cover the copy.
- Judge mailboxes on replies and bounces, not on the warmup tool’s health score.
Deliverability only gets the email seen. Our outbound service handles what comes next: each week we research your target accounts, find a reason each one would talk now, and write every message by email and LinkedIn. Your seller reviews and sends. For the wider picture on inbox placement, see our glossary entry on email deliverability.
Frequently asked
What is the best email warmup tool?
If you already send cold email from Instantly, Smartlead, lemlist or Apollo, the best warmup tool is the one in your sending platform, because it is already paid for. If you send from a tool without warmup, or want inbox placement tests as well, a standalone tool such as Warmup Inbox, MailReach or Warmbox fits. Choose on price per inbox at your inbox count, not on rankings.
What is the best free email warmup tool?
Few are free. Warmup Inbox lists a $0 Freemium plan on its pricing page, and most sending platforms offer a free trial that includes warmup. In practice, warmup comes free with a cold email platform you are already paying for: Instantly lists unlimited warmup on every Outreach plan, and lemlist includes lemwarm in all plans.
Does email warmup actually work?
It helps a new mailbox start sending at a low, steady volume and build some engagement history. It does not replace authentication, a clean list or wanted email. Gmail and Yahoo judge senders on SPF, DKIM, DMARC, spam complaint rates and unsubscribe handling. We found no independent study of warmup networks; the tests published by vendors are small and run by companies that sell the tools.
How much do email warmup tools cost?
Standalone tools charge per inbox. On their own pricing pages, checked on 30 October 2026: Warmup Inbox from $15 per inbox a month billed annually, MailReach $19.5 per mailbox a month, and Warmbox from $15 a month for one inbox. Cold email platforms include warmup in a flat plan: Instantly from $47 a month ($37.60 billed yearly) with unlimited email accounts.
Can warmup fix emails going to spam?
Only if the cause is a new mailbox with no history. If SPF, DKIM or DMARC fail, if your spam complaint rate is above 0.3%, if you send to bad addresses, or if people do not want the email, warmup will not fix it. Check authentication and complaint rates in Google Postmaster Tools first.
Should you keep warmup running after a campaign starts?
Many teams keep it running at a low volume alongside campaigns. We found no independent evidence on how much it helps after the first weeks. Watch reply and bounce rates per mailbox; a mailbox whose reply rate drops is a better signal than any warmup score.
