Maildoso is worth it if you need a lot of cheap SMTP mailboxes and already pay for a sequencer and a warmup tool. It sells mailboxes and sending infrastructure rather than campaigns, so the monthly price covers only part of a working setup.
Prices and limits below come from maildoso.com and its knowledge base, checked on November 6, 2026.
What Maildoso sells
Maildoso runs its own SMTP servers instead of reselling another provider's. It manages MX, SPF, DKIM and DMARC for your domains and sends through one shared IP pool that rotates as reputation changes. It also provisions Google Workspace mailboxes on domains Google accepts, though the cheap default is an SMTP mailbox capped at 15 cold emails a day.
The rest of the product is plumbing: a Master Inbox for replies, domain and mailbox creation by API or MCP, pre-warmed domains, inbox placement tests every three days, and one-click export to Instantly, Smartlead, Saleshandy, EmailBizon and lemlist. Campaign building stays in your sequencer.
That split matters. Maildoso's help centre states that warmup does not run in Maildoso and is not included in a plan. You warm the mailboxes in a third-party tool and pay that vendor separately.
Maildoso pricing
| Plan size | Monthly price | Mailboxes | Cost per mailbox |
|---|---|---|---|
| 30 mailboxes | $75 | 30 | $2.50 |
| 300 mailboxes | $225 | 300 | $0.75 |
| 1,000 mailboxes | $499 | 1,000 | $0.49 |
Quarterly plans still exist at legacy rates: 32 mailboxes and 8 domains for $299 a quarter, 68 mailboxes and 17 domains for $499, and 400 mailboxes and 100 domains for $2,199. Pre-warmed domains cost $11.90 each per month and carry up to 50 mailboxes and 750 emails a day, which suits a campaign with a fixed start date.
Every plan lists a 30-day money-back guarantee. Maildoso also advertises a refund if deliverability falls below 80%, a vendor promise rather than a measured result.
The limits that decide the cost
Maildoso publishes exact per-mailbox numbers, and they differ from most sequencer defaults. An SMTP mailbox should send 15 campaign emails a day including follow-ups, with warmup running at 80 a day from the first day. Total sending is capped at 100 emails a day per mailbox, and a mailbox that crosses it is deactivated automatically.
Limits apply per mailbox, not per domain. Maildoso recommends 20 to 50 SMTP mailboxes per domain and says up to 99 is fine. A domain with 20 mailboxes therefore carries 300 cold emails a day.
That cap drives the real cost, because a cheap mailbox that sends 15 a day needs more mailboxes than one that sends 30.
| Provider | Cost per mailbox | Emails per day | Cost per 1,000 emails |
|---|---|---|---|
| Google Workspace | $5.00 | 30 | $165 |
| Azure tenants | $0.50 | 2 | $250 |
| Maildoso SMTP | $0.49 | 15 | $33 |
The figures are Maildoso's, and they price each provider at its own daily ceiling. The gap holds at most volumes: 1,000 emails a day needs 67 Maildoso mailboxes, or about $33 a month at list price, against $165 for Google Workspace.
Warmup is the hidden line item
A Maildoso plan does not warm anything. You connect the mailboxes to Instantly, Plusvibe or EmailBison and pay that tool's subscription on top.
The warmup tool you pick changes the settings you can run. Maildoso's help centre notes that Plusvibe and EmailBison cap warmup at 50 emails a day, that EmailBison will raise the cap to 100 on request, and that it does not recommend Smartlead's warmup pool for Maildoso SMTP mailboxes. If Smartlead is already your sequencer, budget for a second tool for warmup or accept lower warmup volume than Maildoso asks for. Our Smartlead review covers what that platform does well on the sending side.
What buyers ask before switching
The longest public write-up is an agency owner on r/SaaS who moved 500 mailboxes off resold Google Workspace after Google wiped out domain sets twice. The setup runs Maildoso SMTP through Instantly at 20 emails a day per mailbox, with about 14 mailboxes in a 14-day cooldown at any time, under 3% of the fleet. The fix was to overprovision by 15% to 20% so a cooldown never leaves a gap in follow-ups.
The same post puts Maildoso at $1.40 per mailbox after negotiation, below the roughly $1.90 volume rate the agency started on, and reports a 2.3% reply rate against 1.8% on Google Workspace in a side-by-side test. Treat that as one agency's numbers on one offer, not a benchmark.
The second question buyers raise is control over IPs. Maildoso offers no dedicated IPs and publishes no IP list. Its help centre says 10% to 20% of its pool sits on a blocklist at any time, that listed IPs are rotated out automatically, and that a static list would be wrong within a day.
Who Maildoso suits
Worth it: agencies and sales teams running 100 or more mailboxes, already on Instantly, Plusvibe or EmailBison, who want mailbox cost near $0.50 and are willing to manage domains and warmup themselves.
Worth it with care: teams that need Google Workspace mailboxes. Switching from Google Workspace to SMTP is supported; switching back needs unused Google Workspace allotment already on the plan.
Not worth it: founders sending from three mailboxes, or anyone who wants one vendor for mailboxes, warmup and campaigns. At that size the setup work costs more than the saving.
Mailboxes are the cheapest part of cold email. Replies come from the list, the offer and the copy, and running all of it, from domains to booked calls, is what an outbound marketing agency takes off your plate.