Cheapest Email Warm-Up per Mailbox: 2026 Cost Table

The cheapest email warm-up per mailbox is $0 at 1, 5 and 20 mailboxes when BobWork supports your provider; at 50 mailboxes, the lowest stated monthly cost is TrulyInbox at $29, then Smartlead at $39, Instantly at $47 and BobWork at $60. Ignore billing units and a cheap headline can mislead you. This guide compares free limits, paid prices, pool type and provider fit.

How should you compare prices?

Prices were read on 3 October 2026 from vendor pricing pages; check before you buy. The tables use the stated cheapest paid plan, free-plan limits, billing unit, pool type, providers and Outlook support from the source set.

Where a vendor did not state mailbox capacity, higher-tier prices or warm-up volume on its pricing page, the table says “n/s”. That means “not stated”, not “expensive”.

This is a cost comparison, not a deliverability ranking. For a broader buying view, see the cheapest email warm-up tools comparison and the free email warm-up tools guide.

Two rules matter before you compare prices.

First, per-mailbox tools scale directly. A $19 mailbox costs $95/month at five mailboxes and $950/month at 50.

Second, account-based tools can look cheap at higher mailbox counts. That only helps if the plan really supports your provider, daily volume and workflow.

Price also does not replace authentication. Google’s sender guidance says to keep spam complaint rates under 0.1% and never at or above 0.3%. Yahoo also requires proper sender authentication for bulk senders. Use primary guidance such as Google’s email sender guidelines and Yahoo’s sender requirements when you set DNS and sending policy.

Which tools are free?

Start with the free limit, not the paid headline. Some tools have a real free-forever plan. Others have only a trial, a spam test or a free feature that is not warm-up.

Among standalone warm-up tools, only TrulyInbox and BobWork Email Warm-up offer a free-forever plan in this source set. TrulyInbox is free for 1 email account and 10 warm-up emails/day. BobWork is free for up to 20 mailboxes, with a 3→30/day ramp per mailbox.

BobWork also has limits you should check. Outlook and Microsoft 365 are not supported yet. Google sign-in shows an unverified-app notice because the CASA audit has not been completed. BobWork uses a shared warm-up network by default; if you switch to a private pool, you need at least two mailboxes.

Cheapest email warm up per mailbox

This table calculates monthly cost at 1, 5, 20 and 50 mailboxes. It uses monthly billing where a monthly price is stated. Annual discounts are shown in the free-limit table, but not used in the main calculation.

At 1 mailbox, the lowest stated cost is $0 from BobWork and TrulyInbox.

At 5 and 20 mailboxes, BobWork is the only tool in this comparison with a stated $0 cost.

At 50 mailboxes, the lowest stated monthly cost is TrulyInbox at $29, followed by Smartlead at $39, Instantly at $47 and BobWork at $60. Treat that ranking as a price screen only. You still need to check provider support, product scope, sending limits and whether you want a warm-up-only tool or a broader outreach platform.

Do not multiply account-level pricing unless the source facts state unlimited accounts or enough mailbox capacity. Do not assume “n/s” means the tool cannot support the count. It means the source facts do not state enough to calculate it.

What does each tool cost?

Use this section to decide which rows deserve a closer look.

BobWork Email Warm-up costs $0 for up to 20 mailboxes and $2/month for each active mailbox above 20. It supports Gmail, Google Workspace, Zoho, Lark, Yahoo, iCloud, SES, SendGrid, Mailgun and generic IMAP+SMTP. The default shared warm-up network can start with one mailbox. A private pool per account is available if you prefer isolation. BobWork does not support Outlook yet.

TrulyInbox has a free-forever plan with 1 email account, 10 warm-up emails/day, basic deliverability tracking and no card. Its Starter plan is listed at $29 monthly or $22/month annually, with unlimited accounts stated in the source facts. Its pricing page lists Outlook support.

Smartlead and Instantly are account-level outreach platforms with warm-up bundled. Smartlead starts at $39/month. Instantly starts at $47/month. Both show low calculated costs at 20 and 50 mailboxes because unlimited accounts are stated in the source facts. Compare the whole platform, not only warm-up.

Warmup Inbox, MailReach, Lemwarm and Folderly use per-mailbox pricing in the source facts. Their costs scale directly with mailbox count. At 50 mailboxes, the monthly calculations are $950 for Warmup Inbox, $975 for MailReach, $1,450 for Lemwarm and $4,800 for Folderly.

Mailwarm is plan-based. Starter is $69/month and covers 1 mailbox. Scale is $479/month and covers 10 mailboxes. The source facts do not state a plan covering 20 or 50 mailboxes, so those cells are marked n/s.

Mailivery, Warmbox, Mails.ai, Warmy and InboxAlly need extra checking before you calculate multi-mailbox cost. Their source rows list starting prices, but not enough mailbox capacity detail to calculate every count here.

Which provider do you use?

Cheap is useful only if the tool can warm the mailboxes you actually send from. Provider support is the first filter.

If you use Outlook or Microsoft 365, remove BobWork from today’s shortlist. Microsoft requires OAuth for this kind of mailbox access, and BobWork does not support Outlook yet. Check Microsoft’s current OAuth documentation before you choose any IMAP-style workaround.

If you use Gmail or Google Workspace, check the OAuth warning and your risk tolerance. BobWork supports Google sign-in with the gmail.modify scope, but Google shows an unverified-app notice. You can also connect Gmail through IMAP with an app password where that is available. For setup details, use the Gmail warm-up guide.

If you use Zoho, Lark, Yahoo, iCloud or SMTP platforms, check the connection method before price. BobWork supports Zoho Mail through Zoho Mail API with a Self Client code, including the free plan, or IMAP on Mail Lite and above. It also supports Lark, Yahoo, iCloud, SES, SendGrid, Mailgun and generic IMAP+SMTP. For Zoho, use the Zoho warm-up guide.

Pool type is the second filter. A shared pool gives a one-mailbox account peers to exchange with. A private pool gives more control, but it needs enough of your own mailboxes. BobWork uses a shared warm-up network by default, or a private pool per account if you prefer.

The free pool does this step automatically: it picks peers, spreads sends across the mailbox time zone and avoids the same pair writing twice within three hours. You should still check DNS and spam landings before adding real outreach volume.

What should you check first?

Before you pay for any warm-up tool, run this small audit. It prevents most pricing mistakes.

Authentication is not optional. Use SPF, DKIM and DMARC before you compare inbox placement. BobWork checks SPF, DKIM and DMARC daily per domain. You can also use the free SPF checker, DKIM checker and DMARC checker.

If a mailbox is already landing in spam, reduce sending before you add more warm-up. BobWork’s published practice is to pause a mailbox above a 5% spam rate for a few days.

How many mailboxes do you need?

At 1 mailbox, the lowest stated cost is $0 from BobWork and TrulyInbox. The practical choice depends on limits. TrulyInbox lists 1 email account and 10 warm-up emails/day. BobWork lists up to 20 mailboxes and a 3→30/day ramp, but does not support Outlook yet.

At 5 mailboxes, BobWork is the only tool in this comparison with a stated $0 cost. TrulyInbox, Smartlead and Instantly have low account-level prices if their provider support and product scope fit.

At 20 mailboxes, BobWork remains $0. Account-based tools stay fixed where unlimited accounts are stated. Per-mailbox tools become materially more expensive.

At 50 mailboxes, BobWork becomes $60/month. TrulyInbox is lower at $29/month if its paid plan, provider support and limits fit your workflow. Smartlead and Instantly are also lower in the table, but they are broader outreach platforms rather than standalone warm-up-only tools.

For a new domain, do not buy 50 mailboxes just to force more volume from one domain. Add domains and mailboxes carefully, then warm them over time. A typical new-domain warm-up period is three to four weeks. Use the new domain warm-up plan if you are starting from zero.

Which option is safest?

The safest cheap option is the one that matches your mailbox count, provider and pool preference without forcing risky volume.

Choose BobWork if you use Gmail, Google Workspace, Zoho, Lark, Yahoo, iCloud, SES, SendGrid, Mailgun or IMAP+SMTP, and you want the lowest stated cost through 20 mailboxes. Use BobWork Email Warm-up with the limits in mind: no Outlook yet, Google’s unverified-app notice for OAuth, shared warm-up network by default, and private pool available when you have at least two mailboxes.

Choose a paid alternative if you need Outlook today, prefer a specific vendor pool, or want warm-up bundled with a broader outreach platform. Use the tables above to calculate the real mailbox cost before you commit.

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