Coldrig vs Maildoso: cheapest raw mailboxes, normalized by daily send cap
We're not going to dodge this one: Maildoso's raw per-mailbox price is the cheapest we've found in this comparison set, and it stays cheaper even after normalizing for its much lower per-mailbox daily sending cap. Choose Maildoso when raw mailbox cost is the dominant factor and you're prepared to run your own sequencing, warmup coordination, and compliance logic on top. Choose Coldrig when you want mailbox provisioning, warmup, campaigns, and replies as one agent-driven lifecycle, with better agent discoverability, at a higher but still bounded price.
Fast decision table
| Requirement | Maildoso | Coldrig |
|---|---|---|
| Raw mailbox price | $0.50–$2.50/mailbox/mo depending on volume; custom volumes from $0.49/mailbox | $19.80/mailbox at 5, down to $10.82/mailbox at 60 (see pricing table below) |
| Per-mailbox daily sending cap | 15 cold emails/day (Google Workspace) or 15 cold/day (SMTP), plus a separate warm-up allowance | Published, server-enforced warmup ramp — 5/day in week one, rising to 40/day once fully warmed on day 29 (see the deliverability guide); 30/day is the conservative planning assumption used for capacity math once warmed |
| Domains included | Included free only on legacy quarterly plans; monthly-plan customers buy separately at $12/year | Included automatically, roughly one domain per 2-3 mailboxes |
| MCP / API access | Included on every plan (resolved above) | Included at every tier |
| Agent discoverability (llms.txt, server-card.json) | Both 404 — no llms.txt, no MCP server-card discovery file found | Both live — llms.txt, server card |
| Unsubscribe / List-Unsubscribe automation | We could not confirm from Maildoso's public site whether this is automatic or a manual per-campaign setting — not asserting either way; verify directly with Maildoso before relying on it for compliance | Suppression and unsubscribe enforced server-side by default |
| Money-back guarantee | 30-day money-back guarantee on every plan | No refunds on the unused portion of a paid period (see Terms) — month-to-month, cancel anytime; paid activation is live in production today |
| Live production track record | Yes — a shipped, live-sending product | Not yet — real sending is live in production as of today (see FAQ), but Coldrig has no established multi-year track record, and mailbox send-authorization completes on our side (everything before that is self-serve and automatic) |
Where Maildoso is honestly stronger
- Raw mailbox economics — by a wide margin. $0.49-$2.50 per mailbox is genuinely the cheapest we've found, and it holds up even after normalizing for the lower daily cap (see the table below). We'd be publishing slop if we hid this.
- Deliverability tooling included at every tier. Self-healing mailboxes, IP rotation, CAPTCHA domain protection, reputation measurement, and free deliverability audits every 3 days are bundled from the entry plan.
- MCP and API access on every plan, including entry-level — no feature-gate to a higher tier for this.
- 30-day money-back guarantee on every plan, a concrete risk-reducer Coldrig doesn't currently publish.
Where Coldrig's design is different
- One managed lifecycle, not just mailboxes. Maildoso sells mailbox infrastructure; sequencing, campaign logic, and reply handling are the customer's own build. Coldrig bundles infrastructure and the sequencing/reply layer behind the same token.
- Domains included by default. Maildoso's monthly plans (the ones with the lowest per-mailbox price) charge $12/year per domain separately; domains are automatically included in Coldrig's mailbox price.
- Agent discoverability. Coldrig publishes both an
llms.txtand a standards-based MCP server-card discovery file; neither resolves on Maildoso's site today.
Pricing, normalized: cost per 100 sends/day
Comparing raw $/mailbox alone is misleading here, because Maildoso's mailboxes are capped at 15 cold emails/day on Google Workspace mailboxes (25/day during warm-up) — well below the 30/day planning assumption used elsewhere on this page for a fully warmed Coldrig mailbox (up to 40/day server-enforced ceiling). Both platforms enforce a per-mailbox daily ceiling; the comparison that matters is the number, not whether a ceiling exists at all. The table below normalizes both platforms to cost per 100 sends of daily capacity, using Maildoso's own published cap and Coldrig's own published planning assumption.
| Platform / tier | Monthly price | Mailboxes | Per-mailbox daily cap | Total daily capacity | Cost per 100 sends/day |
|---|---|---|---|---|---|
| Maildoso — 30 mailboxes | $75 | 30 | 15/day | 450/day | $16.67 |
| Maildoso — 300 mailboxes | $225 | 300 | 15/day | 4,500/day | $5.00 |
| Maildoso — 1,000 mailboxes | $499 | 1,000 | 15/day | 15,000/day | $3.33 |
| Coldrig — 5 mailboxes | $99 | 5 | ≈30/day (planning assumption) | ≈150/day | $66.00 |
| Coldrig — 20 mailboxes | $249 | 20 | ≈30/day (planning assumption) | ≈600/day | $41.50 |
| Coldrig — 60 mailboxes | $649 | 60 | ≈30/day (planning assumption) | ≈1,800/day | $36.06 |
Even normalized, Maildoso is substantially cheaper per unit of daily sending capacity. Coldrig's per-mailbox planning assumption (≈30 sends/day) is not a purchased allowance or contractual guarantee — actual safe daily volume depends on warmup stage, mailbox health, and provider rules, exactly as it would on any platform (see what counts as a mailbox). Neither platform sells send credits as a metered product: Maildoso's per-mailbox price includes its 15/day technical ceiling, and Coldrig's mailbox price includes its own server-enforced ramp ceiling (up to 40/day) — Coldrig has no send quota on top of that; sends themselves are not the billing meter on either platform. The honest reason to pay more per unit of capacity on Coldrig is the layer above the mailbox: sequencing, reply handling, suppression, and agent-native discoverability bundled into the same price, not sold separately or left to your own build.
Bottom line
If raw mailbox cost is the dominant constraint and you're prepared to build or bring your own sequencing, warmup coordination, and compliance logic, Maildoso is a genuinely better deal — we'd rather say so clearly than dress up a losing number. If the requirement is one agent-driven lifecycle across infrastructure, campaigns, and replies, with domains bundled and agent discovery files that actually resolve, Coldrig is doing more per dollar even though the sticker price is higher.
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