Atomic Mail vs Email Spam Tester

A side-by-side comparison built from both listings. Blank cells mean the company has not given that detail; we never guess.

Atomic Mail compared with Email Spam Tester
Detail	Atomic Mail	Email Spam Tester
What it does	Email API for AI agents	Test real inbox placement and 42 technical checks with no signup required
Stage	Beta	Established
Founded	Not given	2026
Based in	EE	Not given
Pricing model	free	freemium
Pricing	Free during open alpha. Accounts created during alpha are migrated to the free tier of the paid product.	Not given
Key features	Agent self-registration via proof-of-work Full JMAP inbox: send and receive MCP server AgentSkill Open IETF standard (RFC 8620/8621) Custom domains Reputation scoring system	Real inbox placement testing in Gmail, Outlook, Yahoo and more 42 technical checks across authentication, infrastructure, content and compliance SPF, DKIM and DMARC verification Blocklist lookup across 20+ DNS blocklists SpamAssassin-compatible spam score Link reputation checking HTML structure analysis Bulk sender rules for Gmail and Yahoo compliance Fix plan with recomputed score for corrections API and MCP server integration options
What makes it different	Reputation-based rate limiting via proof-of-work	Two independent spam engine scores instead of one, including Gmail and Yahoo 2024 bulk sender rules Fix plan recomputes points by scoring corrected message rather than estimating No account, signup or credit card required to run tests Built by practitioner with years of live sending infrastructure debugging experience
Free plan	Not given	Not given
Open source	Not given	Not given
Platforms	Not given	Not given
Public API	Not given	Not given
Community votes	0	0
DR (Domain Rating by Ahrefs)	30 no change since last check	18 no change since last check
Trust Flow (Majestic)	21	17
Citation Flow (Majestic)	32	25
Referring domains (Majestic)	265	35

5 details filled in for both companies.

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