API archive entry · source-reported
PostStack
EU-hosted email API for transactional and marketing email, with contacts, broadcasts, and analytics
Other Email APIs
These records share a directory category and are ordered by similarity of reported access facts. They are a shortlist, not proof of drop-in compatibility.
inboxsink
Disposable inboxes for end-to-end tests that wait for the email and extract OTP codes
API key · HTTPS reported · CORS No
Atomic Mail
Email for AI agents: programmatic inbox creation and send/receive over JMAP
API key · HTTPS reported · CORS Unknown
Cloudmersive Validate
Validate email addresses, phone numbers, VAT numbers and domain names
API key · HTTPS reported · CORS Yes
Email Validation
Validate email addresses for deliverability and spam
API key · HTTPS reported · CORS Yes
EmailJS
Send emails directly from client-side JavaScript without a backend server
API key · HTTPS reported · CORS Yes
ImprovMX
API for free email forwarding service
API key · HTTPS reported · CORS Unknown
How to compare them
Coverage
Compare exact endpoints, fields, geography, history, and update frequency.
Operating cost
Model request volume, caching, overages, support, and migration cost.
Integration risk
Test auth, errors, pagination, latency, versioning, and outage behavior.
Data rights
Review attribution, redistribution, retention, privacy, and commercial-use terms.
Source reference
This page separates source-reported facts from questions that need live provider verification.