Comparison
WarmInboxes vs Puzzle Inbox
Puzzle Inbox: Google Workspace and Outlook 365 (provider claims)
WarmInboxes column checked 2026-10-17 against /price.md, /how-it-works and /offer. Puzzle Inbox column: checked 2026-11-11 against its own pages at puzzleinbox.com.
| Criterion | WarmInboxes | Puzzle Inbox |
|---|---|---|
| Price | Prewarmed Google or Microsoft $6–$8 per inbox per month by billing cycle, free prewarmed .COM/.CO domain included. Azure tenants $50–$69 per month for up to 100 inboxes. Fresh inboxes on your own domains: Google $2.00–$3.50, Microsoft 365 $2.00–$3.00, Azure tenant $50. (source) | Google standard $3/inbox/mo, warmed $4.50; Outlook 365 standard $0.35, warmed $0.50; up to 100 Outlook per domain. (source: puzzleinbox.com/pricing) |
| Provider type | Official, licensed Google Workspace, Microsoft 365 and Microsoft Entra (Azure) tenants. Isolated per customer: no shared tenants, you hold admin on every mailbox. (source) | Google Workspace and Outlook 365 (provider claims) (source: puzzleinbox.com/pricing) |
| Setup time | Delivered within 48 to 72 hours of payment, prewarmed and fresh alike, DNS included. Prewarmed sends the day it lands; fresh after 14 to 21 days of warmup. (source) | 24–72 hours with DNS setup. (source: puzzleinbox.com/pricing) |
| Domain ownership | Prewarmed orders include a prewarmed .COM or .CO domain registered by us; fresh orders run on domains you own or buy through us. The Terms of Service set out the domain term and what cancelling does to it. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: Who registers the domain, who owns it, and what happens to it if you cancel? |
| DNS setup | SPF, DKIM, DMARC and forwarding configured before handover and verified by hand against a delivered message, on every platform. (source) | DNS configured. (source: puzzleinbox.com/pricing) |
| Warmup | Prewarmed inboxes arrive already warmed. Fresh inboxes are warmed by our technicians for 14 to 21 days. Once the inboxes are connected to your sequencer, its own warmup is switched on and runs alongside your campaigns, and we switch ours off, so the mailboxes are never warmed by two systems at once. An AI agent sends but does not warm, so tell us the inboxes are going to an agent: we keep them in our warmup pool for free, or you can connect an external warmup tool. (source) | Warmed plans optional; duration not stated. (source: puzzleinbox.com/pricing) |
| API access | REST API at api.warminboxes.com/v1 with read, write and orders:place scopes, a one-file CLI, and a sandbox where test keys run the same routes without charging. Reference published verbatim on this site. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: Is there a documented API to order, read build state and export mailboxes, with a sandbox? |
| MCP support | Two MCP servers: a keyless public one exposing every free deliverability check read-only, and an authenticated one on the account that previews and places orders, follows builds and exports into sequencers. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: Can an AI assistant act on the account through an MCP server, and is the free diagnostic layer reachable without a key? |
| Sequencer integration | Direct export into Instantly, Smartlead, PlusVibe and EmailBison from the portal or the API; any IMAP/SMTP or OAuth tool from the credentials you hold. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: Which sequencers can mailboxes be exported into directly, and what does the export need? |
| Support | 24/7 WhatsApp with operators who run cold email campaigns themselves, plus email. No ticket queue. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: What channel, what hours, and who answers: operators or a ticket queue? |
| Replacement policy | The 7-Day Placement Replacement Guarantee. Follow the sending requirements, and if an eligible newly delivered inbox fails our placement standard (warm primary inbox placement) during its first seven days, we replace that inbox at no charge. Send us the evidence (a placement test, bounces or headers) within those seven days and our team assesses it. Placement itself is not guaranteed: the receiving providers make every filtering decision. Replacements after the first week are not free. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: What happens when an inbox stops landing: replaced, on what terms, in what time? |
| Testing methodology | Published: a dated placement test log with senders and seed accounts, a SURBL blocklist study and a Google sender reputation study by top-level domain, each with sample sizes and what the method cannot see. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: Is placement testing published, with dates, senders, seed accounts and sample sizes? |
| Real observations | Our own agency sends more than a million cold emails a month on this infrastructure, and the studies above are drawn from that sending. (source) | Not published on Puzzle Inbox’s own pages when read on 2026-11-11. Ask them: Does the provider send cold email on this infrastructure themselves, at what volume, and is any of it published? |
Where Puzzle Inbox may be the better choice
- Low-cost Outlook for very low daily sending volume.
Verify it yourself: read both pricing pages the same day, put the thirteen questions to their support, and run a ten-inbox thirty-day test on each. All comparisons →