Instantly and Warmup Inbox both offer email warmup, but warmup plays a different role in each product. Instantly is a cold email sending platform that includes warmup. Warmup Inbox is a deliverability platform designed to get more of your emails into the inbox.
That focus shows in the results. In our testing, Warmup Inbox achieved 20% better deliverability on average for Google inboxes than Instantly.
Instantly includes unlimited standard warmup with paid Outreach plans starting at $47 per month. Its own documentation says the Standard Pool consists of other Instantly users who have enabled warmup. Instantly also offers a Premium Pool of aged Google and Microsoft accounts for an additional $500 per month.
Warmup Inbox starts at $15 per inbox per month annually. Its network includes more than 30,000 inboxes, and Pro adds custom warmup settings, scheduled warmup, specific ESP warmup and warmup in 12 languages.
Both products can warm inboxes and run cold email campaigns. Instantly gives you more tools around prospecting and sales management.
Warmup Inbox gives you a lower entry price and more ways to tailor the warmup process without paying for a broader outreach subscription.
Instantly is a cold email outreach product with campaign sequencing, a B2B lead database, CRM features, Unibox, email verification, AI sales tools and email warmup.
Warmup comes with paid Outreach plans instead of a standalone warmup subscription. The Standard Pool is available with those plans, while Instantly sells access to its Premium Pool separately.
Instantly includes standard warmup with every paid Outreach plan, but not all of its warmup and deliverability options are included in that subscription.
Instantly’s help center says its Standard Pool consists of other Instantly users who have enabled warmup. Connected mailboxes exchange warmup emails and generate engagement signals designed to build sending activity.
Paid Outreach plans include standard warmup for unlimited email accounts.
Our take: Peer-to-peer warmup isn't unusual, and Warmup Inbox also uses connected inboxes within its network. The more important question is what happens inside that network and how much control you have over the warmup process.
Instantly lets you set a daily warmup limit and reply rate. Advanced settings include weekday-only warmup, read emulation, open rate, spam protection, marking messages as important and warming a custom tracking domain.
Our take: Instantly covers the main warmup settings. Warmup Inbox Pro adds custom schedules and templates, specific ESP warmup, custom ramp settings and warmup in 12 languages.
Instantly’s Premium Pool uses aged Google and Microsoft accounts. Instantly says it generates 9% more replies than its Standard Pool, based on its own data.
Premium is included with pre-warmed and Done-For-You accounts. Customers using other accounts can add Premium Pool access for $500 per month.
Our take: Instantly reserves its aged-account pool for Premium customers. That makes the quality and performance you get from the included Standard Pool an important part of the buying decision.
Instantly’s Inbox Placement product tests where emails land across different providers. It also checks SPF, DKIM and DMARC and monitors domains and IPs against 94 blacklists. These features are separate from the warmup included with Outreach.
Our take: Instantly gives you useful deliverability diagnostics, but they sit outside its standard Outreach warmup. Warmup Inbox keeps placement testing, blacklist monitoring and warmup together.
Instantly also sells pre-warmed accounts from $10 per month and domains from $15 per year. Its pre-warmed and Done-For-You accounts include Premium Pool access.
Our take: Instantly has plenty of options for building out a cold email stack, but the costs can add up once you move beyond standard warmup.
Instantly doesn’t sell standard warmup on its own. It comes with paid Outreach plans, starting at $47 per month for Growth.
Pricing is current as of September 2026. Please verify pricing before purchase.
Unlimited connected accounts don't make the Growth plan unlimited in every respect. Growth includes 5,000 emails per month, so teams also need to consider campaign volume when comparing costs at scale.
Warmup Inbox starts at $15 per inbox per month with annual billing. Higher tiers increase daily warmup volume and add more control over how your inboxes warm.
Volume discounts lower the per-inbox price as you add accounts, with self-serve pricing available through 50 inboxes and custom pricing above that.
Warmup Inbox Pro costs $49 per inbox per month annually, just $2 more than Instantly’s $47 Outreach Growth plan. Pro adds custom warmup settings and schedules, custom templates, specific ESP warmup and multilingual warmup.
Instantly’s biggest advantage is that standard warmup comes with its paid Outreach plans. The limitations become clearer when warmup and deliverability are the main reason you’re shopping.
Instantly has a 4.8 out of 5 rating on G2. Positive reviews mention its simple setup, campaign management and ability to work across multiple inboxes.
The picture on Trustpilot is less positive. Instantly’s rating is currently unavailable following a guidelines breach, and Trustpilot says it removed fake reviews from the page. Negative reviews raise issues with billing, account access and customer support.
Reviews on both sites cover Instantly as a whole, not its warmup feature alone.
The products overlap on warmup and campaign sending, but the similarities start to thin out once you look at controls, pricing and the wider tools included with each subscription.
Both products use connected inboxes as part of their warmup networks. Instantly explicitly describes its Standard Pool as other Instantly users who have enabled warmup. Its Premium Pool uses aged Google and Microsoft accounts.
Warmup Inbox has more than 30,000 active inboxes in its network. On average, emails warmed through Warmup Inbox reach the Primary inbox 15% more often than with other warmup tools.
Winner: Warmup Inbox. Both use peer-to-peer warmup, but Warmup Inbox gives you its full warmup network without splitting access between Standard and Premium pools.
Instantly lets you adjust daily volume, reply rate and several engagement signals.
Warmup Inbox lets you control starting volume, daily increases and maximum volume. Pro adds custom schedules and templates, specific ESP warmup and warmup in 12 languages.
Winner: Warmup Inbox. Both give you control over warmup activity, but Warmup Inbox adds more options for tailoring warmup to your sending setup and audience.
Warmup Inbox starts at $15 per inbox per month annually. Instantly starts at $47 per month, with standard warmup included in the Outreach subscription.
At almost the same price as Instantly Growth, Warmup Inbox Pro adds the advanced warmup controls covered above. Instantly has the advantage when the number of connected inboxes is the main consideration, although Growth’s 5,000-email monthly allowance still limits campaign sending volume.
Winner: Warmup Inbox. It has the lower entry price and gives you a dedicated warmup option without requiring an Outreach subscription.
Both Instantly and Warmup Inbox support cold email campaigns. Warmup Inbox offers multi-step sequences, contact imports, sending windows, daily limits, A/B testing and a unified inbox, with warmup continuing while campaigns run.
Instantly also supports campaign sending alongside its wider outreach and sales tools.
Winner: Tie. Both products give you the core tools to build, send and manage cold email campaigns.
Warmup Inbox connects directly to your mailbox, so you can use it alongside Instantly or another sending tool.
Instantly’s standard warmup requires a paid Instantly Outreach plan.
Winner: Warmup Inbox. You can add it to your existing setup without moving your outreach workflow into another product.
Warmup Inbox keeps deliverability at the center of the product. You can monitor where your emails land and adjust how your warmup runs without buying a larger sales stack.
You also don't need to rebuild your cold email workflow around Warmup Inbox. Use it for warmup and deliverability alongside your existing tools, or run sequences directly from your account.
Teams that want more control over sender reputation can get it without paying for prospecting and CRM features they may never use.
"I've been using WarmupInbox.com to warmup all of our company emails and it works great and is the most affordable option that I've found. Support is great and responds quickly if you ever have any issues or need help."
"A great UI comparing with the price and how the system works makes it the best warm-up tool I've ever used."
"Really like Warmup Inbox. Easy to use, great deliverability and great after sales service."
Stick with Instantly’s built-in warmup if:
Instantly’s built-in warmup covers the basics for teams already using its outreach tools. More control over the warmup process and deliverability is where a dedicated product starts to earn its place.
Instantly builds warmup into its wider outreach product. Warmup Inbox starts with warmup and deliverability, giving you more control over how your inboxes warm while still supporting cold email campaigns.
Warmup Inbox lets you tailor warmup to your provider, sending schedule and audience, then monitor deliverability alongside it. You can run your campaigns here too or keep using the outreach tools already in your stack.
If deliverability is important enough to actively manage, Warmup Inbox gives it a product of its own.
Start 7-day free trialNot on its own. Standard warmup comes with paid Instantly Outreach plans, which start at $47 per month.
Premium Pool access costs $500 per month for customers using other accounts. It is included with Instantly’s pre-warmed and Done-For-You accounts.
Yes. Instantly offers a 14-day free trial without requiring a credit card.
Yes. Warmup Inbox connects to your mailbox independently, so you can use it for warmup while continuing to send campaigns through Instantly.
Yes. Pro and Max support warmup in 12 languages.
Not as part of standard Outreach warmup. Instantly offers Inbox Placement separately for placement testing and other deliverability checks.
Warmup Inbox has the lower starting price at $15 per inbox per month annually. Instantly starts at $47 per month and includes standard warmup for unlimited connected accounts, so the cost comparison changes as you add inboxes.
Last updated September 2026. Pricing and features can change. We review this comparison regularly and recommend checking each provider's current pricing before making a purchase.
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