Email on Acid

Email on Acid is a comprehensive email pre-deployment testing platform designed to help email marketers and developers deliver flawless email campaigns across all devices and email clients. Originally founded as an independent email testing company, Email on Acid was acquired by Pathwire (which also owned Mailgun and Mailjet) and subsequently became part of Sinch in 2021 when the Swedish communications platform acquired Pathwire for $1.9 billion. Now operating as Sinch Email on Acid, the platform serves over 100,000 customers worldwide including major brands like Microsoft, Wikipedia, and American Express, helping them send perfect emails through automated testing and optimization tools.

The platform offers unlimited email testing across 100+ email clients and devices including desktop, mobile, and tablet environments with live client previews rather than emulations, ensuring emails render exactly as subscribers will see them. Key features include Campaign Precheck with comprehensive pre-deployment validation covering accessibility compliance (WCAG/ADA), link validation, image optimization, HTML code verification, and spam filter testing against 23 major filters including Gmail, Outlook, and Yahoo. Additional capabilities include dark mode testing and optimization, collaborative review tools with shareable test links and team comments, email analytics with engagement tracking and geolocation data, blocklist domain testing to protect IP reputation, and click-to-fix editing tools that allow non-technical users to resolve issues without HTML coding experience.

Ideal for email marketing teams, digital agencies, eCommerce companies, and email developers who need to ensure consistent email rendering and deliverability across diverse email environments. Email on Acid serves businesses requiring enterprise-grade email testing with unlimited usage, comprehensive pre-flight checks, and team collaboration features for complex email production workflows. The platform is particularly valuable for organizations sending high-volume campaigns, managing multiple brands, or operating under strict accessibility and compliance requirements, especially those needing to reduce email production time, prevent deliverability issues, and maintain professional brand consistency across all email touchpoints.