An inbox warming tool sends and receives automated messages from your mailbox to build activity before a cold campaign. MailReach, Instantly and lemlist’s lemwarm each do this, but they price it in different ways: per mailbox, bundled into a platform, or included with a seat. This comparison sets out what each vendor publishes and what none of them can replace.
The short version
MailReach is a standalone warm-up and spam testing product priced per mailbox. Instantly and lemlist bundle warm-up into their sending platforms. Pick by what you already pay for and how many mailboxes you run. No tool replaces authentication, a clean list or sensible volume, and the effectiveness claims on every vendor page are the vendor’s own.
What an inbox warming tool does
According to lemlist, lemwarm exchanges messages with a network of active inboxes across providers, generating opens and replies, and occasionally rescues messages from spam. It adjusts volume to your campaign activity so warm-up and outreach do not compete for daily send limits. Other tools describe the same mechanism in their own words. That is a vendor description, and the pages we reviewed contain no independent data.
| Tool | How it is priced | What the page says is included | Where the figure comes from |
|---|---|---|---|
| MailReach | $19.50 per mailbox per month on All-In-One, with annual billing saving 20% | Automated warm-up, a spam tester, a reputation dashboard and domain and inbox health checks | MailReach pricing page |
| Instantly | Growth plan at $47 a month, or $37.60 a month on annual billing | Unlimited email accounts and unlimited warm-up, inside the sending platform, with 5,000 emails a month | Instantly pricing page |
| lemwarm (lemlist) | Included with every lemlist seat at no extra cost, according to lemlist | Warm-up that adapts to campaign activity, plus a Deliverability Hub | lemlist blog, a vendor source. No seat price in the article |
| Apollo | Warm-up uses credits beyond one free mailbox | Email warm-up as one of several credit-consuming actions | Apollo help center |
A worked cost example
The arithmetic below is ours and uses list prices at monthly billing. It compares products that do different jobs, because Instantly includes the sending platform and MailReach does not. The point is how the pricing models scale with mailboxes.
| Mailboxes | MailReach All-In-One | Instantly Growth |
|---|---|---|
| 1 | $19.50 | $47 |
| 5 | $97.50 | $47 |
| 10 | $195 | $47 |
| 20 | $390 | $47 |
With one or two mailboxes, a per-mailbox tool is cheaper than a platform plan. As the number of mailboxes grows, a plan with unlimited accounts becomes cheaper, provided you want its sending tools as well. If you already use a sending platform with built-in warm-up, a separate tool may only be worth it for the spam testing.
What no warming tool can replace
Warm-up adds activity, but Google’s sender guidelines still require SPF and DKIM to pass, a DMARC record, and a user-reported spam rate below 0.1%. Start with the SPF, DKIM and DMARC explainer, then clean the list as described in B2B email verification, and keep volume inside the limits in how many cold emails per day per domain.
Our warm-up timeline guide shows that vendors disagree on how long warm-up takes, from two weeks to thirty days, and that one vendor calls real replies the strongest positive signal. An automated network can generate activity, but it cannot replace people who want your message. MailReach itself says that consistently sending under 20 cold emails per inbox per day may not need warm-up at all.
How to choose between them
- Count your mailboxes, because per-mailbox pricing scales with them and platform pricing mostly does not.
- Check whether your sending platform already bundles warm-up before buying a second product.
- Decide whether you need spam tests and placement reports, which MailReach lists and platform plans may not.
- Look for stated limits. MailReach’s example plan lists up to 100 emails a day, while Instantly and lemlist state no warm-up cap on the pages we reviewed.
- Treat every effectiveness claim as marketing until you have seen your own placement results.
Questions about inbox warming tools
Do I need an inbox warming tool?
Not always. MailReach says consistently sending under 20 cold emails per inbox per day may not need warm-up, and you can ramp volume manually over three to four weeks. A tool saves effort at scale but does not replace authentication or a clean list.
How much does inbox warming cost?
It depends on the model. MailReach lists $19.50 per mailbox per month, Instantly includes unlimited warm-up in plans from $47 a month, and lemlist says lemwarm is included with every seat. Prices change, so check each vendor page.
Does Instantly include warm-up?
Yes. Its pricing page lists unlimited email warm-up on the Growth plan at $47 a month, or $37.60 a month on annual billing, alongside unlimited email accounts and 5,000 emails a month. Check the live page, because some plan labels on it have been inconsistent.
Is lemwarm free?
lemlist says lemwarm is included with every lemlist seat at no extra cost, so it is bundled rather than free. Seat pricing sits on lemlist’s pricing page, and the vendor article states no per-day cap for warm-up.
Can a warming tool guarantee inbox placement?
No. The claims on vendor pages are the vendors’ own, and the pages we reviewed include no independent data. Authentication, list quality and sending volume still decide placement, and real replies remain the strongest signal.
Bottom line
Choose a warming tool by pricing model and by what you already pay for, not by effectiveness claims. Fix authentication and list quality first, ramp volume deliberately, and treat the tool as a way to save effort rather than a way to skip the groundwork.
Related reading
- How long to warm up an email domain: the timelines vendors give and the signals that matter
- Why do my emails go to spam: the diagnostic order
- Email bounce rate: the thresholds that decide whether a platform acts
