Best Cold Email Mailbox Providers (2026): Prices Compared

A cold email mailbox provider sells you the sending inboxes themselves, usually on domains it registers for you, with SPF, DKIM and DMARC already published. As of October 6, 2026 the cheapest options run from about $0.49 to $3 per mailbox per month, and the right pick depends on how many mailboxes you need and whether you want real Google or Microsoft inboxes or a provider's own servers. We sell one of these (Warmerly OneMail), so this page says plainly where a competitor is the better choice.

Per-mailbox prices at a glance

Which provider fits which sender

Maildoso: the cheapest at volume

At 300 mailboxes Maildoso lists $0.75 each, and $0.49 at 1,000. That is below anything else here at scale. The entry tier is 30 mailboxes at $2.50 each, domains are extra ($12 a year, rising to $15 in October 2026), and each mailbox is limited to 15 cold or 80 warmup emails a day. It offers a 30-day money-back guarantee on monthly packages. If you are building hundreds of mailboxes and have your own warmup, this is the number to beat.

InboxKit: real Google and Microsoft mailboxes, no minimum

InboxKit sells official Google Workspace and Microsoft 365 mailboxes from $2.50 to $3.00 each, with no minimum, automatic SPF, DKIM and DMARC, and an API. Some senders trust Google and Microsoft inboxes more than a provider's own servers, and this is the way to get them cheaply. Warmup is a separate $3 per mailbox per month, which roughly doubles the cost, and there is no free trial.

Primeforge and Infraforge: slots, with a 10-slot minimum

Both sell in slots with a 10-slot minimum and about $14 a year for domains. Primeforge sells Google Workspace and Microsoft 365 mailboxes at $113 a month for 10 slots ($94 on annual billing). Infraforge lists $4 per slot on annual billing and sells a dedicated IP as an add-on at $99 a month. Neither pricing page states warmup, and neither offers a trial. Both recommend about 30 emails a day per mailbox, with a hard maximum of 100.

Mailreef: a whole server

Mailreef sells a dedicated server with its own IP and 150 or more mailboxes for $240 a month on a 12-month term ($249 flexible), plus a tenth of a cent per send. At full use that is about $1.60 per mailbox. It suits senders who want an IP nobody else shares and are willing to run at server scale.

Warmerly OneMail: no minimum, and warmup built in

OneMail registers your sending domain, publishes MX, SPF, DKIM and DMARC, creates the mailboxes and connects them to warmup without extra steps. Pricing is $2.99 per mailbox per month on Starter, $1.99 on Growth and $0.99 on Agency, with no minimum number of mailboxes. A OneMail mailbox never uses one of the mailbox slots in your plan. We also keep ready-warmed mailboxes in stock for people who want to send immediately. Domains are billed separately when you register one through us.

How to choose

• Under 30 mailboxes and you want warmup included: OneMail or InboxKit with the warmup add-on. Compare the totals, because InboxKit's add-on doubles the line price.
• 30 to 300 mailboxes on a budget: Maildoso, as long as you bring your own warmup.
• You specifically want Google or Microsoft inboxes: InboxKit (no minimum) or Primeforge (10 slots).
• You want an IP that nobody else uses: Mailreef or Infraforge's dedicated IP add-on.
• You are an agency running many client domains: price the Agency tier of OneMail against Maildoso at your real mailbox count.

Whatever you buy, plan for warmup

A new mailbox on a new domain has no reputation, and every provider above says so in its own limits: 30 cold emails a day per mailbox is the common recommendation, and Maildoso asks for at least 14 days of warmup first. The mailbox is only the container. Whether your mail reaches the inbox depends on warmup, authentication and list quality, which is the part most buyers underestimate.