Mails.ai vs mailX (2026): Pricing, Features & Which to Choose

Who comes out ahead

Based only on the facts in our directory. The right pick still depends on the job you need done.

Lower starting price
Not comparable
Not comparable: Mails.ai does not list a price
Free plan
Tie
Both have one
Higher rating
Mails.ai
4.0 against 3.8
Same job?
Yes
Both are AI Infrastructure & Agent Tooling tools

Side by side

Compared on	Mails.ai	mailX
Our rating	4.0Better	3.8
Starts at	Free	Free
Free plan	Yes	Yes
Category	AI Infrastructure & Agent Tooling	AI Infrastructure & Agent Tooling
Plans	Free	Free
Key features	Email API designed for AI agents Prompt injection scoring on inbound messages Sender reputation graph Opt-in intent and entity classification MCP server integration	One-click SPF, DKIM, DMARC, MX, and blacklist checks Consolidated deliverability report explaining spam placement causes No signup or API key required for web use JSON API for programmatic access MCP server for direct use by AI agents
Pros	Injection scoring addresses the most exposed surface agent inboxes have Structured reply events rather than raw message parsing Opt-in classification is a sound privacy default	Free with no signup barrier for a fast deliverability check MCP server access is a differentiator most deliverability checkers lack Backed by a Y Combinator company with deliverability-specific focus since 2020
Cons	An injection score raises the floor; it is not a guarantee Agents still need their own limits on acting without confirmation Infrastructure requiring engineering to adopt	Narrow single-purpose scope rather than a full email marketing or sending platform No paid tier means no dedicated support commitment for the tool itself Deeper deliverability fixes still require action outside the tool, such as DNS changes or IP warmup
Company	Mails.ai	Mailwarm, founded 2020

Prices come from each vendor's pricing page, last checked 20260901. Check the vendor before you buy.

FAQ

Questions people ask

Is Mails.ai better than mailX?

In our reviews Mails.ai scores 4.0 and mailX scores 3.8. The better pick depends on the job. Mails.ai: Email infrastructure built for AI agents - every inbound message arrives scored for prompt injection and sender reputation. mailX: Free email deliverability checker that diagnoses SPF, DKIM, DMARC, and blacklist issues in one report.

Which is cheaper, Mails.ai or mailX?

Mails.ai: free. mailX: free.

Do Mails.ai and mailX have free plans?

Yes, both have a free plan.

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