The best email warmup tools depend on what your sender already does. OXYGEN suits teams that want inboxes with warm-up included, placement tests (where a test email lands) and timed follow-ups by email, LinkedIn or WhatsApp. Instantly, Smartlead and lemlist warm every inbox you connect at no extra cost. MailReach, Warmy, lemwarm and Warmbox are standalone services, worth it only for tests or reports your sender lacks. Before any cold email, check each inbox's authentication, warm-up days and placement.
By Tim Scheuer, Co-founder of Oxygen · Checked November 10, 2026
Usually not. Warm-up means a new inbox trades emails with a pool of inboxes that open and reply, which Instantly says helps Gmail and Outlook trust it. Instantly, Smartlead and lemlist warm the inboxes you connect; OXYGEN includes warm-up in each inbox's price. Buy a separate tool only for a gap: placement tests, reputation reports or inboxes your sender cannot warm. With no independent warm-up benchmark, we rank by fit and cost. OXYGEN wrote this list and is on it.
| Tool | Kind | Price per inbox a month | Placement or reputation tests | Works with | Starts at |
|---|---|---|---|---|---|
 OXYGENGo-to-market (GTM) platform, inboxes and warm-up built in | Included with managed or connected inboxes | Included: $4 for a managed inbox, $1 for your own | Placement monitoring $1 an inbox a month with 2 tests; Google inboxes only | Google Workspace and Microsoft 365 inboxes, bought or connected | Warm-up included; managed inbox $4 a month, on a paid plan from $49 |
 InstantlyCold email sender with warm-up bundled | Bundled in a sending tool | $47 a month covers unlimited inboxes | 2 free placement tests, then from $47 a month; warm-up health score | Inboxes from any provider, plus its own done-for-you inboxes | Growth $47 a month, or $37.60 yearly, with unlimited inboxes and warm-up |
 SmartleadCold email sender with warm-up bundled | Bundled in a sending tool | $39 a month covers unlimited mailboxes | SmartDelivery from $49 a month for 120 tests | Google, Outlook and SMTP mailboxes (other email providers) | Base $39 a month, or $32 yearly, with unlimited mailboxes and warm-up |
 lemwarmWarm-up in lemlist, or standalone per inbox | Bundled in lemlist, or standalone | Included with lemlist; standalone $29, or $24 yearly | Deliverability reports (whether mail reaches the inbox); placement tests in lemlist at 100 credits | lemlist, or Gmail, Outlook and other providers on their own | Included with lemlist; standalone $29 per inbox a month, or $24 yearly |
 MailReachStandalone warm-up with spam tests | Standalone service | $25 each for 1 to 5 inboxes; $19.50 for 6 to 20 | 20 spam test credits included; reputation dashboard | Google, Outlook and SMTP inboxes, beside any sender | $25 per inbox a month for 1 to 5; $19.50 for 6 to 20 |
 WarmyStandalone warm-up and deliverability suite | Standalone service | From $49 a month by warm-up volume; no per-inbox price shown | Shared placement test credits, reputation tracker, Google Postmaster data (Gmail's spam-rate reports) | Gmail, Outlook and SMTP inboxes, beside any sender | From $49 a month, priced by warm-up volume |
 WarmboxStandalone warm-up priced by inbox count | Standalone service | $19 for 1 inbox; $79 for 3; $159 for 6 | Spam score monitoring; DNS and blacklist checks | Gmail, Microsoft 365, Yahoo, Zoho, Amazon SES and any SMTP inbox | Solo $19 a month for 1 inbox, or $15 yearly; Growth $159 for 6 |
OXYGEN Go-to-market (GTM) platform, inboxes and warm-up built inBest for: Teams that want inboxes, warm-up, placement checks and email sequences (timed follow-ups that stop on a reply) on one bill, with warm-up included in each inbox's price.
OXYGEN sells Google Workspace and Microsoft 365 inboxes at $4 a month each, warm-up included. An inbox you connect gets warm-up in its $1 monthly connection. Warm-up starts at 1 email a day and climbs to 10. A new inbox's cold sending ramps from 5 to 10 to 20 a day before its daily limit. Mailboxes need a paid plan; the email setup guide covers domains, DNS and the warm-up wait.
Instantly Cold email sender with warm-up bundledBest for: Teams that send cold email from many inboxes and want warm-up for all of them inside one flat sending plan.
Instantly includes unlimited email accounts and warm-up on every Outreach plan, from Growth at $47 a month or $37.60 billed yearly. Inboxes join a pool of Instantly users who open and reply to warm-up emails. Its help center calls an inbox ready after 2 weeks of warm-up, or 3 for AirMail, accounts on Instantly's own mail system. Placement tests across Gmail, Outlook and Yahoo start with 2 free, then an add-on from $47 a month.
Instantly website · Oxygen vs Instantly: the full comparison
Smartlead Cold email sender with warm-up bundledBest for: Volume senders and agencies that connect many mailboxes and want warm-up and placement tests from one vendor.
Smartlead includes unlimited mailboxes and a warm-up pool on every plan, from Base at $39 a month or $32 billed yearly. Higher plans get a higher pool tier. It also sells Google and Outlook mailboxes from $4.50 a month each, plus a yearly domain fee. Its help center advises at least 14 days of warm-up, and counts warm-up emails toward each mailbox's daily cap. Placement tests come from SmartDelivery, an add-on from $49 a month for 120 tests.
Smartlead website · Oxygen vs Smartlead: the full comparison
lemwarm Warm-up in lemlist, or standalone per inboxBest for: lemlist users, who get it on every plan, and teams that want per-inbox warm-up with deliverability reports outside their sender.
Every lemlist plan includes lemwarm, from the $69 a month Email plan with unlimited senders. On its own, lemwarm costs $29 per inbox a month on Essential, or $24 billed yearly. Smart, at $49, warms with your real email templates. Both include a setup check and deliverability reports. It connects Gmail and Outlook in one click, and other providers such as Zoho.
MailReach Standalone warm-up with spam testsBest for: Teams that want warm-up for a set number of inboxes, with spam tests and a reputation dashboard, apart from their sender.
MailReach prices warm-up per inbox: $25 a month each for 1 to 5 inboxes and $19.50 for 6 to 20, with 20% off yearly. Every plan includes 20 spam test credits, a reputation dashboard and blacklist, SPF, DKIM and DMARC checks. A spam test shows where a test email lands, by provider. It warms Google, Outlook and SMTP senders such as Amazon SES.
Warmy Standalone warm-up and deliverability suiteBest for: Teams that want placement tests, Google Postmaster data and DMARC monitoring next to warm-up, across several sending tools.
Warmy's plans start at $49 a month and are priced by the volume of warm-up emails; its pricing page shows no price per inbox. They include placement test credits shared across mailboxes, a reputation tracker, Google Postmaster data and DMARC monitoring. Warmy asks buyers to confirm the monthly test allowance with its team. It connects Gmail, Outlook and SMTP inboxes, with a 7-day free trial.
Warmbox Standalone warm-up priced by inbox countBest for: A founder or small team warming one to six inboxes, on providers from Gmail and Microsoft 365 to Zoho, Amazon SES or any SMTP inbox.
Warmbox prices warm-up by inbox count. Solo is $19 a month for one inbox at 50 warm-up emails a day. Start-up is $79 for 3 inboxes and Growth $159 for 6, or $15, $69 and $139 billed yearly. Every plan includes spam score monitoring and DNS and blacklist checks. It connects Gmail, Microsoft 365, Yahoo, Zoho, Amazon SES and any SMTP inbox.
| If you need | Pick |
|---|---|
| Inboxes with warm-up included, and sequences that pair email with LinkedIn or WhatsApp | OXYGEN |
| Warm-up for every inbox inside one flat cold email plan | Instantly |
| Warm-up plus placement tests that cover many sender accounts at once | Smartlead |
| Warm-up inside lemlist, or per inbox with reports outside your sender | lemwarm |
| Per-inbox warm-up with spam tests, beside any sender | MailReach |
| Placement tests, Postmaster data and DMARC monitoring next to warm-up | Warmy |
| Low-cost warm-up for a few inboxes on Zoho, SES or other SMTP services | Warmbox |
An inbox is ready when three checks pass. Its domain passes SPF, DKIM and DMARC, the DNS records that prove your domain sent the email. It has warmed for at least 14 days. And a placement test of your real email lands in the inbox. Instantly and Smartlead both name 2 weeks as the minimum, and OXYGEN's recommended setup waits 2 to 4 weeks. Google gives no day count; it says to start low and raise volume slowly.
Start the clock early. Tim Scheuer's August 2026 GTM framework says to warm up "in parallel of all that sourcing", so inboxes are ready when the list is. In July 2026 the OXYGEN co-founder announced OXYGEN inboxes with "warmup and inbox placement tests built in". Today warm-up is in each inbox's price, and placement monitoring is an add-on.
Now price an illustrative team of ten new inboxes, made up for this example. Warm-up on MailReach costs $195 a month (10 × $19.50), with 20 spam test credits. On Instantly's $47 Growth plan, warm-up for all ten is included. On OXYGEN, each managed inbox at $4 a month includes warm-up, on a paid plan from $49. MailReach's figure is warm-up alone and Instantly's adds sending; neither includes inboxes, which OXYGEN's price covers, paid from plan credits.
So a team on Instantly that adds MailReach pays twice for warm-up. What it gains is spam tests and a reputation dashboard. Instantly sells placement tests itself: 2 free, then $47 a month. Buy the test, not a second warm-up.
All three must pass on the inbox's domain. Google requires them for bulk senders. Outlook.com rejects mail from domains sending over 5,000 a day that fail them. A fail means fix, not send.
Count days since warm-up began, at about 10 warm-up emails a day. Under 14 days is a hold. Instantly wants 3 weeks for AirMail inboxes; OXYGEN's setup waits for 28 days of confirmed warm-up sends when most recipients use Microsoft.
Send the email you will actually send to test inboxes at Gmail and Outlook. A warm-up score is not this test: Instantly and lemlist both say theirs does not show campaign placement.
Go when all three pass: start at about 5 cold emails a day and climb slowly. Hold when warm-up is under 14 days or untested: keep warming. Fix when a check fails or the test lands in spam: fix it, keep warming, test again.
Leave warm-up on after go. Smartlead counts warm-up and cold emails together toward each mailbox's daily cap, and OXYGEN warns when the two pass 50 a day.
Paste this header into a sheet, split it into columns at the commas, and fill one row per inbox. Inbox, provider, domain, SPF/DKIM/DMARC, warm-up tool, warm-up start, days warmed, warm-ups a day, placement result, cold sends a day, decision, cost per inbox a month.
| Inbox | SPF, DKIM, DMARC | Warm-up so far | Placement test | Decision |
|---|---|---|---|---|
| Inbox 1: Google, example.com Illustrative | All pass | Since Oct 13: 28 days, 10 a day | Inbox at Gmail and Outlook | Go: 5 cold emails a day, rising to 15 |
| Inbox 2: Microsoft 365, example.net Illustrative | All pass | Since Oct 30: 11 days, 10 a day | Not run yet | Hold: keep warming to day 14, then test |
| Inbox 3: Google, example.org Illustrative | DMARC missing | Since Oct 20: 21 days, 10 a day | Spam at Outlook | Fix: add DMARC, keep warming, test again |
| Your inbox | Pass or fail | Start date, days, warm-ups a day | Inbox, spam or not run | Go, hold or fix |
Instantly and Smartlead warm unlimited inboxes from $47 and $39 a month, and every lemlist plan includes lemwarm. Standalone, MailReach charges per inbox with spam tests, Warmy adds placement tests and Postmaster data, and Warmbox starts at $19 for one inbox. OXYGEN includes warm-up in each inbox it sells or connects.
At least 2 weeks. Instantly asks for 2 weeks, or 3 for its AirMail inboxes, and Smartlead for at least 14 days. OXYGEN's recommended setup waits 2 to 4 weeks, and 28 days of confirmed warm-up sends when most recipients use Microsoft. Google gives no day count. Confirm with a placement test before the first cold email.
Often nothing extra: Instantly ($47 a month), Smartlead ($39) and lemlist ($69) include it for the inboxes you connect. Standalone, lemwarm is $29 per inbox a month and MailReach $25, or $19.50 each for 6 to 20. Warmbox is $19 for one inbox, and Warmy starts at $49 by volume. OXYGEN includes it in each inbox's price.
Free warm-up is mostly a trial: 14 days on Instantly and lemlist, 7 on Warmy. That covers 2 weeks at best, so budget for a paid plan before your first cold email. The free checks are worth using: Instantly's 2 placement tests, MailReach's spam test and Warmbox's blacklist and DNS checker. OXYGEN's free plan cannot run mailboxes.
For most teams on Instantly, yes. Every plan warms unlimited inboxes, and it calls an inbox ready after 2 weeks with a health score above 90%. That score counts warm-up emails only. What a separate tool adds is placement tests and reputation reports, and Instantly sells tests too: 2 free, then $47 a month.
Only once it passes the readiness check, and then slowly. Keep warm-up running and count it in the daily total: Smartlead counts both toward each mailbox's cap. OXYGEN ramps a new inbox from 5 to 10 to 20 cold emails a day over nine sending days. It warns when warm-up and cold emails pass 50 a day.
A bad list, missing SPF, DKIM or DMARC, and emails people mark as spam. Bounces from unchecked addresses hurt a warm domain too, so verify recipients first. Google asks senders to keep their spam rate below 0.1% and never reach 0.3%. No tool on this list can promise the inbox, OXYGEN included.
Yes. An inbox bought in OXYGEN costs $4 a month with warm-up included. An inbox you connect gets warm-up in its $1 monthly connection. Mailboxes need a paid plan, from $49 a month. Placement monitoring is an add-on at $1 an inbox a month for Google inboxes. See pricing for the plans.
We make OXYGEN, so it comes first and you should read this as an interested list. We chose the other email warmup tools ourselves, and each entry says who it suits.
Facts and prices for every tool but OXYGEN come from its vendor's own pages, such as its website, pricing and docs. We checked them on the dates below. OXYGEN's facts and prices come from the product and its live price list.
The products named here are trademarks of their owners and are not affiliated with OXYGEN. Something out of date? Tell us.