Maildoso review: SMTP packs down to $0.49 a mailbox, a 15-a-day cap and warm-up left to you

Maildoso sells SMTP mailboxes in packs of 30, 300 and 1,000, and at 1,000 the price falls to $0.49 a mailbox. In return each mailbox sends up to 15 cold emails a day, warm-up comes from another tool, and the money-back guarantee pays out in one narrow case.

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  • Warm-up and sending included
  • $2.50 a mailbox, 12 minimum
  • Month-to-month billing

Maildoso at a glance

Price per mailbox
from $0.49 on the 1,000 plan; $2.50 on the 30 plan
Smallest order
30 mailboxes, $75 a month, on the standard plans
Mailbox types
SMTP
Warm-up
Not provided; 14+ days in an outside tool such as the Instantly pool, kept running
MCP server
Hosted MCP server at mcp.maildoso.com, same token as the API
Trustpilot
3.5 / 5 from 3 reviews

Who Maildoso fits

Pick Maildoso if

  • You already run warm-up in another tool and send under 15 a day per mailbox
  • You already pay for a sequencer with warm-up
  • You send only to company addresses
  • You want an MCP server and API on every plan

Look elsewhere if

  • You want more than 15 cold emails per mailbox a day
  • You want warm-up from your mailbox vendor
  • You need Google Workspace or Microsoft 365
  • You want a refund policy that covers more than outages

What Maildoso is

Maildoso runs its own mail servers and IP pool. You get SMTP mailboxes on domains bought through Maildoso or connected from elsewhere, with IP rotation, self-healing (a mailbox that burns comes off campaigns for 14 days) and placement tests every three days.

There is no sequencer and no warm-up. Mailboxes sync in one click to Instantly, Smartlead or EmailBison, export as CSV for nine other tools, or go out through the API. The terms require at least 14 days of warm-up in a third-party tool before the first campaign.

Google Workspace is listed as a product but is closed to new mailboxes, and we found no Microsoft option. Maildoso is an SMTP vendor.

SMTP mailboxes on Maildoso's own servers and IPs, priced in mailbox packs, exported to a sending tool you pay for separately source (opens the vendor's page in a new tab) Run by BacklinkSwappers, Inc. (d/b/a Maildoso), San Francisco; terms under Delaware law source (opens the vendor's page in a new tab)

Maildoso pricing

Maildoso plans and prices
PlanPriceMailboxesPer mailboxBillingIncludes
30 mailboxes$75 a month30$2.50monthlyIP rotation, self-healing mailboxes, placement tests, API and MCP; domains extra source (opens the vendor's page in a new tab)
300 mailboxes$225 a month300$0.75monthlySame features; domains extra source (opens the vendor's page in a new tab)
1,000 mailboxes$499 a month1,000$0.49monthlySame features; domains extra source (opens the vendor's page in a new tab)
32 mailboxes + 8 domains$299 a quarter32$3.10quarterly (legacy)Domains included source (opens the vendor's page in a new tab)
68 mailboxes + 17 domains$499 a quarter68$2.40quarterly (legacy)Domains included source (opens the vendor's page in a new tab)
400 mailboxes + 100 domains$2,199 a quarter400$1.80quarterly (legacy)Domains included source (opens the vendor's page in a new tab)

List prices from Maildoso's pricing page, checked . Taxes and card fees excluded.

The three monthly packs are $75 for 30 mailboxes ($2.50 each), $225 for 300 ($0.75) and $499 for 1,000 ($0.49). The steps are steep: 31 mailboxes means either the 300 pack or a custom count bought in the app, whose price is not published.

Read the price together with the sending cap. At 15 cold emails a day, 1,000 emails a day takes 67 Maildoso mailboxes; at 25 a day it takes 40. So the 300 pack ($225) is the honest comparison for a team sending 1,000 to 4,500 a day, plus a warm-up tool and a sequencer.

Domains are not in the monthly packs. The terms put renewal at $15 a domain a year since October 1, 2026, while the pricing FAQ still shows $12 next to a note about the change.

Maildoso limits, setup and terms

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

Other Maildoso features

Self-healing mailboxes
Burned mailboxes come off campaigns for 14 days; IPs are replaced when they stop working source (opens the vendor's page in a new tab)
Placement tests
Every 3 days, with a health score per mailbox source (opens the vendor's page in a new tab)
Placement guarantee
Aims for 80% inbox placement; up to 4 free domain replacements within a year of purchase source (opens the vendor's page in a new tab)
Free audits
Copy checks for spintax and spam words source (opens the vendor's page in a new tab)
Recipient rules
Terms prohibit sending to personal webmail such as Gmail or Yahoo addresses source (opens the vendor's page in a new tab)
Scale (vendor's claim)
10M+ emails a day, 400k+ mailboxes, 7,000+ companies source (opens the vendor's page in a new tab)

In detail

The money-back guarantee, read closely

The pricing page advertises a 30-day money-back guarantee on monthly packs. The terms in force since October 1, 2026 pay it in one situation: your mailboxes fail to send for 3 or more consecutive days through Maildoso's fault, within 30 days of the first payment.

A refund is also refused if you sent more than 15 cold emails a mailbox a day, warmed up for less than 14 days or sent without an unsubscribe link. Domains are never refunded. Treat it as an outage guarantee.

Rules that shape who can use it

The terms prohibit sending to personal webmail addresses such as Gmail or Yahoo accounts and require bounce rates under 2%. Maildoso is built for B2B lists of company addresses.

Domains bought through Maildoso are registered to Maildoso while you are a customer; it transfers them to you for free on request. Maildoso's 80% inbox placement target comes with up to four free domain replacements within a year.

Maildoso ratings

Three Trustpilot reviews is too few to read much into. Maildoso's home page cites a 4.7 G2 rating from 197 reviews; G2 did not load for us, so we could not check it.

Maildoso or Outreach2day

We sell cold email mailboxes too. Where our product fits this buyer and where it does not.

Outreach2day fits if

  • You run 1,000+ mailboxes: we quote a volume price below every vendor list price in our comparisons, warm-up and sending included
  • You want 25 cold emails per mailbox a day and fewer mailboxes for the same volume
  • You want warm-up and a sending engine without a second and third bill
  • You need 12 to 30 mailboxes and Maildoso's smallest pack is 30

Stay with Maildoso if

  • You want a pre-built done-for-you campaign service

Maildoso review: questions

How much does Maildoso cost?

$75 a month for 30 mailboxes, $225 for 300 and $499 for 1,000. Domains, warm-up and a sequencer are extra. Legacy quarterly packs with domains are $299, $499 and $2,199 a quarter.

How many emails can a Maildoso mailbox send?

Up to 15 cold emails and 80 warm-up emails a day, ramped up from 1 a day per the terms.

Does Maildoso do warm-up?

No. The terms require at least 14 days of warm-up in a third-party tool, such as the Instantly warm-up pool, kept running afterwards.

Does Maildoso have an MCP server?

Yes. A hosted MCP server at mcp.maildoso.com that uses the same personal access token as the REST API.

What does a Maildoso domain cost?

$15 a year since October 1, 2026, per the terms. The pricing FAQ still mentions $12.

Is Maildoso's money-back guarantee real?

It exists, but the terms limit it to mailboxes that fail to send for 3+ days in a row through Maildoso's fault, within 30 days. Domains are never refunded.

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. Running 1,000+ mailboxes? We also quote a volume price below every vendor list price in our comparisons, warm-up and sending included.

  • Review your domains, DNS records and current inbox placement
  • Size the setup: domains, mailboxes per domain and daily volume per mailbox
  • Plan warm-up and the move from your current provider or sequencer
  • 1,000+ mailboxes: a volume price per mailbox for your setup

Free call

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

Or open the booking page

More on Maildoso

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.

First cold emails on day 14, full volume on day 21

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