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What is Mailwarm?
Mailwarm is an email warmup and deliverability platform that automatically builds sender reputation by generating real engagement signals (opens, replies, important marks) across a network of 50,000+ aged real inboxes. Founded in 2020 and backed by Y Combinator, it helps teams warm up new domains and inboxes before scaling outbound campaigns, with expert deliverability guidance included in every plan.
Mailwarm news
mailX ChatGPT Plugin Approved
mailX by mailwarm received approval as a ChatGPT plugin in approximately 6 hours after submission on October 14, 2026. The plugin allows users to diagnose deliverability issues directly within ChatGPT.
Source: LinkedIn / Thami Benjelloun (CEO) ↗Mailwarm 2.0 Launched
Mailwarm released a major upgrade combining automated warmup, real inbox interactions, 24/7 inbox-placement monitoring, and expert deliverability guidance. New features include warmup with custom content and infrastructure checks via mailX integration.
Source: Product Hunt / Thami Benjelloun ↗mailX by mailwarm Launched for AI Agents
mailX, a free deliverability diagnostic platform for humans and AI agents, launched with web, API, and MCP endpoints. Helps diagnose why emails go to spam and provides fixes for SPF, DKIM, DMARC, and blacklist issues.
Source: Y Combinator Launches ↗Acquired by mailX
Mailwarm was acquired by mailX, a deliverability platform founded by Thami Benjelloun and team. The acquisition strengthens mailX's mission to provide a full-stack email deliverability ecosystem combining warmup, diagnostics, expert consulting, and training.
Source: GlobeNewswire ↗
Key features
5 Positive Signals Per Interaction
Each warmup email generates opens, replies, mark-as-important, remove-from-spam, and bounce-rate improvement signals to build real sender reputation
24/7 Live Inbox Placement Tracking
Real-time monitoring shows whether emails land in inbox or spam, with provider-specific data for Gmail and Outlook reported separately
Expert Deliverability Calls
1 expert call per month on Starter, 4 per month on Growth, on-demand on Scale; Tailored plan includes a dedicated deliverability expert
Account Manager & Setup Support
Every customer gets an account manager to help with SPF/DKIM/DMARC configuration, deliverability audit, and ongoing optimization
Multi-Provider Support
Works with Gmail, Google Workspace, Outlook, Microsoft 365, Yahoo, Zoho, and custom SMTP providers
Spam Score Monitoring
Dashboard shows real-time spam signals and inbox placement trends across email providers
Mailwarm pricing
Mailwarm prices per plan batch (1, 3, or 10 mailboxes) rather than per-inbox. Annual billing offers 12-16% discount versus monthly. No free trial, but warmup begins immediately upon connecting an inbox. Extra interactions beyond plan limits cost $0.02 each.
| Plan | Price | What's included |
|---|---|---|
| Starter | $69/month (annual) or $79/month (monthly) | 1 mailbox, 50 warmup emails/day, 1 expert call/month, account manager, spam score monitoring |
| Growth | $159/month (annual) or $189/month (monthly) | 3 mailboxes, 200 warmup emails/day, 4 expert calls/month, account manager, 2 users |
| Scale | $479/month (annual) or $549/month (monthly) | 10 mailboxes, 500 warmup emails/day, expert calls on demand, account manager, 5 users |
| Tailored | Custom pricing | Unlimited mailboxes, users, warmup volume, plus dedicated deliverability expert managing strategy end-to-end |
Pros & cons
Pros
- + Expert deliverability consulting included in every plan—not an upsell
- + Real inbox engagement from 50,000+ aged real mailboxes, not fake accounts
- + 24/7 live inbox-placement monitoring (not just periodic polling)
- + Clean, simple interface with minimal setup friction
- + Account manager for SPF/DKIM/DMARC configuration help
- + Multi-provider support (Gmail, Outlook, Microsoft 365, etc.)
- + Established brand with 6+ years of history since Y Combinator S20
- + Warmup content adapts to provider behavior for more natural delivery
Cons
- − High per-inbox cost (roughly $48–$69 per mailbox monthly on Scale plan)
- − No free trial before full monthly commitment
- − Warmup pool reported as ~1,000 accounts—smaller than some competitors, may create repetitive patterns ESPs recognize
- − Warmup email content is templated and generic by design
- − Multiple G2 and independent reviews flag weaker Outlook/Microsoft 365 performance
- − Limited analytics depth; users request stronger performance-trend reporting
- − Warmup alone cannot fix broken authentication or missing domain history
- − Requires continuous use to maintain deliverability gains
Who is Mailwarm best for?
- • Small teams warming 1–3 important inboxes before scaling outbound
- • Founders and sales leaders new to email deliverability who want expert hands-on help
- • Agencies managing multiple client inboxes across providers
- • B2B cold outreach and sales sequences starting from new or inactive domains
- • Teams recovering from spam placement and needing expert diagnosis
- • Users sending heavily through Gmail or Google Workspace (strongest provider support)
Frequently asked questions
Is there a free trial?
No. Mailwarm does not offer a traditional free trial, but warmup begins immediately upon connecting an inbox to any paid plan. You can cancel anytime with no lock-in contract.
Can I cancel anytime?
Yes. You can cancel whenever you want with no hidden conditions or long-term commitments.
What payment methods do you accept?
All major payment methods are supported. Cryptocurrency payment is available on request by contacting support.
How long does warmup take to work?
Early improvements may appear within days or weeks. More stable and consistent inbox placement typically takes 2–4 weeks of continuous warmup.
How many mailboxes can I warm with one plan?
Starter includes 1 mailbox, Growth includes 3, and Scale includes 10. Growth and Scale plans allow additional users and mailboxes upon request to support.
