Warmbox alternatives: warmup for more than 6 inboxes, priced at 2,500 emails a day

Warmbox warms 1 inbox for $15 a month, 3 for $69 and 6 for $139, the figures its pricing page shows with Monthly billing selected; above 6 inboxes or 500 warmup emails a day it quotes. It sells no mailboxes or sequencer and publishes no API. Sending 2,500 cold emails a day takes about 100 mailboxes, well past its largest plan. 100 Outreach2day mailboxes send that volume with warmup and our sequencer for $171.67 a month. We make Outreach2day and list it first.

Price 100 mailboxes1,000+ mailboxes? Book a call
  • Warmup and sending included
  • $2.50 a mailbox, 12 minimum
  • Month-to-month billing

Full setup · 2,500 cold emails a day

USD a month
  1. Outreach2dayOutreach2day: $171.67
  2. InboxKitInboxKit: from $286
  3. ZapmailZapmail: $432.83
  4. Mission InboxMission Inbox: from $504
  5. TrulyInboxTrulyInbox: from $576
  6. MailReachMailReach: from $673
  7. lemwarmlemwarm: from $1,924
Mailboxes, domains and the sequencer each one needs to send, at list prices. Line items and sources

Ranked

Why each one is a Warmbox alternative

We make Outreach2day and list it first.

  1. 1. Outreach2day: warmup for as many mailboxes as you buy

    Warmup runs on every mailbox for its whole life, inside $2.50 a month, $1.50 from 100 and $0.50 from 1,000, with our own sequencer and 25 cold emails a mailbox a day from day 14. Google and Outlook placement tests come with each mailbox. Our mailboxes run on our own infrastructure and land in the inbox.

    Per mailbox a month

    from $0.50

    1,000+ mailboxes

  2. 2. Zapmail: Google or Microsoft mailboxes with warmup handled

    Plans of $39 for 10, $99 for 30 and $299 for 100 mailboxes a month, warmup handled per its FAQ, pre-warmed options and an MCP server. No refunds except duplicate billing.

    Zapmail reviewZapmail alternatives

    Per mailbox a month

    from $2.99

    Pro, monthly

  3. 3. InboxKit: per-mailbox billing with a $3 warmup add-on

    Google or Microsoft at $3 a month from one mailbox, Isolated Warmup $3 more. At 6 mailboxes that is $36 against Warmbox's $139 for warmup alone.

    InboxKit reviewInboxKit alternatives

    Per mailbox a month

    from $3

  4. 4. Mission Inbox: high-volume senders who want warmup per mailbox

    Its own mailboxes on dedicated IPs from $50 for 15, MI Premium Warmup at $2 a mailbox a month and metered sends. Separate sending environments per client.

    Mission Inbox reviewMission Inbox alternatives

    Per mailbox a month

    from $1.50

    Scale, mailboxes above 5,000; $3 from 31 to 1,000

  5. 5. TrulyInbox: a standalone warmup tool with no inbox cap

    Unlimited connected accounts, priced by warmup emails a day from $29 to $1,650, a free plan for one account, a 7-day trial and a public API.

    TrulyInbox alternatives

    Per mailbox a month

    from $3.98

    Scale, $199 for the 50 inboxes it suggests

  6. 6. MailReach: warmup with spam tests up to 100 mailboxes

    $25 a mailbox a month down to $16 from 51, spam test credits included, a quote above 100, an API and an MCP server.

    MailReach alternatives

    Per mailbox a month

    from $16

    warmup only, 51–100 mailboxes

  7. 7. lemwarm: teams already sending from lemlist

    $29 an address a month on its own and included free in every lemlist plan for 3 to 5 addresses. No refunds for a started month.

    lemwarm alternatives

    Per mailbox a month

    from $29

    Essential, one address

Side by side

Warmbox and 7 alternatives side by side

Lowest published per-mailbox price, smallest order, mailbox types, warmup, API and MCP. Each cell links its source.

List prices from Outreach2day's pricing page, Zapmail's pricing page, InboxKit's pricing page, Mission Inbox's pricing page, TrulyInbox's pricing page, MailReach's pricing page, lemwarm's pricing page and Warmbox's pricing page, checked . Taxes and card fees excluded.

Cost

What 2,500 cold emails a day cost with each option

The same emails a day for every option: each vendor's mailboxes at its own sending limit, its domains and the sequencer they need, at list prices.

2,500 a day · 55,000 a monthMailboxes, domains and the sequencer · USD a month
  1. Outreach2dayOutreach2day: $171.67
  2. InboxKitInboxKit: from $286
  3. ZapmailZapmail: $432.83
  4. Mission InboxMission Inbox: from $504
  5. TrulyInboxTrulyInbox: from $576
  6. MailReachMailReach: from $673
  7. lemwarmlemwarm: from $1,924
Per 1,000 cold emailsThe same total per 1,000 of the 55,000 emails a month · USD
  1. Outreach2dayOutreach2day: $3.12
  2. InboxKitInboxKit: from $5.20
  3. ZapmailZapmail: $7.87
  4. Mission InboxMission Inbox: from $9.16
  5. TrulyInboxTrulyInbox: from $10.47
  6. MailReachMailReach: from $12.24
  7. lemwarmlemwarm: from $34.98
Outreach2day all-in100 mailboxes · 25 cold emails a day each, warmup and our sequencer included$171.67 a month$3.12 per 1,000 emails · 100 mailboxes for 2,500 emails a day
  • 100 mailboxes at $1.50 (volume price from 100), warmup and sequencer included: $150
  • 20 domains at $13 a year: $21.67
Zapmail + Instantly100 Google or Microsoft mailboxes · 25 cold emails a day each$432.83 a month$7.87 per 1,000 emails · 100 mailboxes for 2,500 emails a day
InboxKit + Instantly63 Google or Microsoft mailboxes · 40 cold emails a day eachfrom $286 a monthfrom $5.20 per 1,000 emails · 63 mailboxes for 2,500 emails a day
Mission Inbox + Instantly84 Mission Inbox (dedicated IPs) mailboxes · 30 cold emails a day eachfrom $504 a monthfrom $9.16 per 1,000 emails · 84 mailboxes for 2,500 emails a day
TrulyInbox + Instantly84 TrulyInbox-warmed mailboxes · 30 cold emails a day eachfrom $576 a monthfrom $10.47 per 1,000 emails · 84 mailboxes for 2,500 emails a day
MailReach + Instantly32 MailReach-warmed mailboxes · 80 cold emails a day eachfrom $673 a monthfrom $12.24 per 1,000 emails · 32 mailboxes for 2,500 emails a day
lemwarm + Instantly63 lemwarm-warmed mailboxes · 40 cold emails a day eachfrom $1,924 a monthfrom $34.98 per 1,000 emails · 63 mailboxes for 2,500 emails a day

Compared at the same emails a day, each vendor at its own published emails per mailbox a day: a cheap mailbox that sends 5 a day costs more per email than one that sends 25. Every option at 2,500 a day · 55,000 a month (22 sending days). Warmbox and its alternatives at the same mailbox count. Mailboxes = emails a day ÷ each vendor's emails per mailbox a day; monthly list prices on monthly billing, with the cheapest plan of the sequencer named in each row that covers the volume (Instantly unless the vendor's mailboxes need another; both include warmup). Domains at each vendor's published price spread over 12 months; "from" means a domain price is not published. A mailbox-only vendor cannot send campaigns on its own, so its total is the full sending setup: its mailboxes, domains and the sequencer plan that covers the volume. Instantly is the reference sequencer, on its published plans for the emails and new contacts a month (emails ÷ 3); Smartlead where Instantly publishes no plan; Mailforge with Salesforge, because its mailboxes cannot be warmed in Instantly. The mailbox line is listed on its own in every cell.

Switching

Move your setup to Outreach2day at 2,500 cold emails a day

We move your mailboxes and campaigns for you, free

New · Outreach2day volume pricing

The mailbox price falls from 100 and again from 1,000 mailboxes

Warmup, the sequencer and the replies inbox included at every tier

  1. Up to 99 mailboxes$2.50a mailbox a month
  2. From 100 mailboxes$1.50a mailbox a month
  3. From 1,000 mailboxes$0.50a mailbox a month

Enterprise plan. Better prices for larger volumes.

Book a call

At scale

From 25,000 to 1,000,000 cold emails a day

The same setups at larger daily volumes. A vendor without a published price at a size reads “Custom pricing (not published)” and has no bar.

Running 25,000+ a day? Enterprise plan: better prices for larger volumes.Book a call

25,000 a day · 550,000 a month1,000 mailboxes · USD a month
  1. Outreach2day all-inOutreach2day all-in: $716.67
  2. Zapmail + InstantlyZapmail + Instantly: $4,066.83
  3. Mission Inbox + InstantlyMission Inbox + Instantly: from $3,858
  4. lemwarm + Instantlylemwarm + Instantly: from $18,831
InboxKit + Instantly, TrulyInbox + Instantly, MailReach + Instantly: no published price at this volume, so no bar.
50,000 a day · 1,100,000 a month2,000 mailboxes · USD a month
  1. Outreach2day all-inOutreach2day all-in: $1,433.33
  2. Zapmail + InstantlyZapmail + Instantly: $8,036.58
  3. Mission Inbox + InstantlyMission Inbox + Instantly: from $7,015.75
  4. lemwarm + Instantlylemwarm + Instantly: from $37,565
InboxKit + Instantly, TrulyInbox + Instantly, MailReach + Instantly: no published price at this volume, so no bar.
100,000 a day · 2,200,000 a month4,000 mailboxes · USD a month
  1. Outreach2day all-inOutreach2day all-in: $2,866.67
  2. Zapmail + InstantlyZapmail + Instantly: $16,064.17
  3. Mission Inbox + InstantlyMission Inbox + Instantly: from $13,004.50
  4. lemwarm + Instantlylemwarm + Instantly: from $75,120
InboxKit + Instantly, TrulyInbox + Instantly, MailReach + Instantly: no published price at this volume, so no bar.
250,000 a day · 5,500,000 a month10,000 mailboxes · USD a month
  1. Outreach2day all-inOutreach2day all-in: $7,166.67
Zapmail + Instantly, InboxKit + Instantly, Mission Inbox + Instantly, TrulyInbox + Instantly, MailReach + Instantly, lemwarm + Instantly: no published price at this volume, so no bar.
500,000 a day · 11,000,000 a month20,000 mailboxes · USD a month
  1. Outreach2day all-inOutreach2day all-in: $14,333.33
Zapmail + Instantly, InboxKit + Instantly, Mission Inbox + Instantly, TrulyInbox + Instantly, MailReach + Instantly, lemwarm + Instantly: no published price at this volume, so no bar.
1,000,000 a day · 22,000,000 a month40,000 mailboxes · USD a month
  1. Outreach2day all-inOutreach2day all-in: $28,666.67
Zapmail + Instantly, InboxKit + Instantly, Mission Inbox + Instantly, TrulyInbox + Instantly, MailReach + Instantly, lemwarm + Instantly: no published price at this volume, so no bar.
Monthly cost of Warmbox and its alternatives from 25,000 to 1,000,000 cold emails a day
Setup25,000 a day550,000 a month1,000 mailboxes50,000 a day1,100,000 a month2,000 mailboxes100,000 a day2,200,000 a month4,000 mailboxes250,000 a day5,500,000 a month10,000 mailboxes500,000 a day11,000,000 a month20,000 mailboxes1,000,000 a day22,000,000 a month40,000 mailboxes
Outreach2day all-in$716.67$1,433.33$2,866.67$7,166.67$14,333.33$28,666.67
Zapmail + Instantly$4,066.83$3,350.16 more$8,036.58$6,603.25 more$16,064.17$13,197.50 moreCustom pricing (not published)Custom pricing (not published)Custom pricing (not published)
InboxKit + InstantlyCustom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)
Mission Inbox + Instantlyfrom $3,858$3,141.33 morefrom $7,015.75$5,582.42 morefrom $13,004.50$10,137.83 moreCustom pricing (not published)Custom pricing (not published)Custom pricing (not published)
TrulyInbox + InstantlyCustom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)
MailReach + InstantlyCustom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)Custom pricing (not published)
lemwarm + Instantlyfrom $18,831$18,114.33 morefrom $37,565$36,131.67 morefrom $75,120$72,253.33 moreCustom pricing (not published)Custom pricing (not published)Custom pricing (not published)

Outreach2day: 25 cold emails per mailbox a day, 5 mailboxes per domain, .com domains at $13 a year (1,000 mailboxes and 200 domains at 25,000 a day; 40,000 and 8,000 at 1,000,000). Instantly and Smartlead with the accounts they sell, at the published plan for the volume; mailbox vendors at their own emails-per-mailbox limit with their domains and the Instantly (Mailforge: Salesforge) plan for the volume. A month is 22 sending days, so emails a month = emails a day × 22. Where a vendor publishes no price at that size the cell says so and the chart leaves it out. At this size the main table's flat $2.50 a Maildoso mailbox gives way to its published packs.

Every line at scale

  • Outreach2day all-in, 25,000 a day: 1,000 mailboxes at $0.50 (volume price from 1,000), warmup and sequencer included ($500) + 200 domains at $13 a year ($216.67) = $716.67
  • Outreach2day all-in, 50,000 a day: 2,000 mailboxes at $0.50 (volume price from 1,000), warmup and sequencer included ($1,000) + 400 domains at $13 a year ($433.33) = $1,433.33
  • Outreach2day all-in, 100,000 a day: 4,000 mailboxes at $0.50 (volume price from 1,000), warmup and sequencer included ($2,000) + 800 domains at $13 a year ($866.67) = $2,866.67
  • Outreach2day all-in, 250,000 a day: 10,000 mailboxes at $0.50 (volume price from 1,000), warmup and sequencer included ($5,000) + 2,000 domains at $13 a year ($2,166.67) = $7,166.67
  • Outreach2day all-in, 500,000 a day: 20,000 mailboxes at $0.50 (volume price from 1,000), warmup and sequencer included ($10,000) + 4,000 domains at $13 a year ($4,333.33) = $14,333.33
  • Outreach2day all-in, 1,000,000 a day: 40,000 mailboxes at $0.50 (volume price from 1,000), warmup and sequencer included ($20,000) + 8,000 domains at $13 a year ($8,666.67) = $28,666.67
  • Zapmail + Instantly, 25,000 a day: Pro + 900 extra mailboxes ($2,999) source (opens the vendor's page in a new tab) + 334 domains at $13 a year ($361.83) + Instantly Hypergrowth + 7 Outbound add-ons (sequencer, warmup) ($706) = $4,066.83
  • Zapmail + Instantly, 50,000 a day: Pro + 1900 extra mailboxes ($5,999) source (opens the vendor's page in a new tab) + 667 domains at $13 a year ($722.58) + Instantly Hypergrowth + 14 Outbound add-ons (sequencer, warmup) ($1,315) = $8,036.58
  • Zapmail + Instantly, 100,000 a day: Pro + 3900 extra mailboxes ($11,999) source (opens the vendor's page in a new tab) + 1,334 domains at $13 a year ($1,445.17) + Instantly Hypergrowth + 29 Outbound add-ons (sequencer, warmup) ($2,620) = $16,064.17
  • Mission Inbox + Instantly, 25,000 a day: Scale $199 + 804 extra mailboxes $2,412 + 541,000 extra sends $541 ($3,152) source (opens the vendor's page in a new tab) + 278 domains, price not published (not published) + Instantly Hypergrowth + 7 Outbound add-ons (sequencer, warmup) ($706) = from $3,858
  • Mission Inbox + Instantly, 50,000 a day: Scale $199 + 1,637 extra mailboxes $4,410.75 + 1,091,000 extra sends $1,091 ($5,700.75) source (opens the vendor's page in a new tab) + 556 domains, price not published (not published) + Instantly Hypergrowth + 14 Outbound add-ons (sequencer, warmup) ($1,315) = from $7,015.75
  • Mission Inbox + Instantly, 100,000 a day: Scale $199 + 3,304 extra mailboxes $7,994.5 + 2,191,000 extra sends $2,191 ($10,384.50) source (opens the vendor's page in a new tab) + 1,112 domains, price not published (not published) + Instantly Hypergrowth + 29 Outbound add-ons (sequencer, warmup) ($2,620) = from $13,004.50
  • lemwarm + Instantly, 25,000 a day: lemwarm Essential for 625 addresses at $29 (the mailboxes themselves not included) ($18,125) source (opens the vendor's page in a new tab) + 125 domains, price not published (not published) + Instantly Hypergrowth + 7 Outbound add-ons (sequencer, warmup) ($706) = from $18,831
  • lemwarm + Instantly, 50,000 a day: lemwarm Essential for 1,250 addresses at $29 (the mailboxes themselves not included) ($36,250) source (opens the vendor's page in a new tab) + 250 domains, price not published (not published) + Instantly Hypergrowth + 14 Outbound add-ons (sequencer, warmup) ($1,315) = from $37,565
  • lemwarm + Instantly, 100,000 a day: lemwarm Essential for 2,500 addresses at $29 (the mailboxes themselves not included) ($72,500) source (opens the vendor's page in a new tab) + 500 domains, price not published (not published) + Instantly Hypergrowth + 29 Outbound add-ons (sequencer, warmup) ($2,620) = from $75,120

Why each plan at scale

Every option is priced for the same 2,500 cold emails a day, each at its own emails per mailbox a day, with Instantly for sending where the vendor has no sequencer. Warmbox has no row: about 100 mailboxes are needed and its published plans stop at 6.

Outreach2day is $171.67 with warmup, the sequencer and 20 domains. InboxKit with Instantly starts at $286 before domains, Zapmail is $432.83 and Mission Inbox from $504. The warmup tools come on top of mailboxes you buy elsewhere: TrulyInbox from $576 and MailReach from $673 with Instantly, lemwarm from $1,924.

Warmbox

Warmbox itself

Each line links to the vendor's page it comes from.

Price per mailbox

source (opens the vendor's page in a new tab)
from $15 a month (Solo, 1 inbox)

Smallest order

source (opens the vendor's page in a new tab)
Solo, 1 inbox at $15 a month

Setup time

source (opens the vendor's page in a new tab)
Connect an inbox in about 2 minutes; 15 to 30 days of warmup before results, per its FAQ

Mailbox types

source (opens the vendor's page in a new tab)
None sold: it warms Google, Outlook and Microsoft 365, Zoho, SendGrid, Mailgun, Amazon SES and any SMTP inbox you own

Sending limits

source (opens the vendor's page in a new tab)
50, 250 or 500 warmup emails a day per plan; 40 a day suggested to start

Warmup

source (opens the vendor's page in a new tab)
Included The product itself: a private network its pages put at 10,000 to 35,000 inboxes

Sequencers

source (opens the vendor's page in a new tab)
No sequencer and no sequencer integration published

MCP server

source (opens the vendor's page in a new tab)
Not published

Refunds

source (opens the vendor's page in a new tab)
Non-refundable, no credits for partly used periods; EU consumers keep a 14-day withdrawal right

Choosing

Why Warmbox users look for an alternative

Scale is the first reason. Warmbox's plans cover 1, 3 or 6 inboxes at about $15 to $23 an inbox; a cold email team at 2,500 a day runs about 100. Above 6 inboxes the price is on request, so you cannot read your bill before a call.

The second is the bill around it. Warmbox warms inboxes you bought elsewhere and sends nothing itself, so the mailboxes, the domains and the sequencer are three more subscriptions. Sequencers such as Instantly already include warmup, and Outreach2day includes it in the mailbox.

Warmbox, MailReach and lemwarm

All three warm mailboxes you already own and charge per mailbox or address: Warmbox $15 to $23, MailReach $16 to $25, lemwarm $29 to $49 a month. TrulyInbox charges by warmup volume with unlimited accounts. Each is compared in MailReach alternatives and lemwarm alternatives.

Whichever you keep, check the result with a placement test on your own copy: every Outreach2day mailbox includes Google and Outlook placement tests, and the best warmup tools post goes through the standalone tools one by one.

Outreach2day

Outreach2day as a Warmbox alternative

We make Outreach2day and list it first. Where it fits and where it does not.

It fits if

  • You run 100+ mailboxes: $1.50 a mailbox from 100 and $0.50 from 1,000, warmup and the sequencer included; larger volumes on the Enterprise plan
  • You warm more than 6 inboxes and want the price published
  • You want mailboxes, warmup and a sequencer in one bill
  • You want $1.50 a mailbox from 100 and $0.50 from 1,000
  • You want Google and Outlook placement tests with every mailbox

It does not fit if

  • You want to warm a mailbox you keep at another provider
  • You need fewer than 12 mailboxes: our minimum order is 12

FAQ

Warmbox alternatives: questions

What is the best Warmbox alternative?

For more than 6 inboxes, mailboxes with warmup included: Outreach2day at $2.50 a mailbox, $1.50 from 100 and $0.50 from 1,000, with our sequencer. If you keep your mailboxes, TrulyInbox warms unlimited accounts by volume and MailReach prices up to 100 mailboxes.

How much does Warmbox cost?

Its pricing page shows $15 a month for 1 inbox, $69 for 3 and $139 for 6 with Monthly billing selected; the toggle switches to $19, $79 and $159 without naming the period. Above 6 inboxes it quotes.

Does Warmbox have an API or a free trial?

Neither is published. Its only free item is a blacklist and DNS checker.

Does Warmbox refund?

Payments are non-refundable and partly used periods earn no credit; EU consumers have a 14-day withdrawal right.

Is Warmbox on Trustpilot?

We found no Trustpilot page for warmbox.ai on 2026-11-02; the Warmbox listings there belong to a UK boiler service.

Deliverability call

Talk to our deliverability team

Book a call with the people who run our mailbox infrastructure. We look at your current setup and tell you what to change. Mailboxes are $1.50 from 100 and $0.50 from 1,000; for larger volumes we size an Enterprise plan with you.

  • Review your domains, DNS records and current inbox placement
  • Size the setup: domains, mailboxes per domain and daily volume per mailbox
  • Plan warmup and the move from your current provider or sequencer
  • Larger volumes: the Enterprise plan and its price for your setup

Free call

See open times in your time zone and book on this page.

Or open the booking page

Related

More on Warmbox

Sources

Each vendor's own pages. Vendors change prices and plans; if something here is out of date, write to support@outreach2day.com and we will fix it.

Outreach2day
Zapmail
InboxKit
Mission Inbox
TrulyInbox
MailReach
lemwarm
Warmbox

Full volume from day 14: 25 cold emails a mailbox a day

Add domains, create mailboxes and turn on warmup. You see every mailbox's warmup numbers from day one.

Book a call