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Mail Tester vs Postmark Spam Check: catalog facts
Mail Tester	Postmark Spam Check
Free Running a test from the website is free.	Free Provided free by Postmark.
Web	Web
No setup beyond sending one email to a given address Simple score out of 10 that is easy to read	Quick SpamAssassin score without running SpamAssassin Usable in the browser or through a JSON API
Tests a single message rather than ongoing deliverability Little detail on the homepage about what each check covers	Only gives a SpamAssassin score, not a full deliverability test Messages are sent to a third-party service for checking
Web application	Web application, Hosted service
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.