API archive entry · source-reported
uchecker
Bulk email verification with full SMTP server responses
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.
Atomic Mail
Email for AI agents: programmatic inbox creation and send/receive over JMAP
API key · HTTPS reported · CORS Unknown
ImprovMX
API for free email forwarding service
API key · HTTPS reported · CORS Unknown
mailboxlayer
Email address validation
API key · HTTPS reported · CORS Unknown
MailboxValidator
Validate email address to improve deliverability
API key · HTTPS reported · CORS Unknown
Mailtrap
Email API and SMTP for sending transactional and bulk emails, with email testing sandbox for safe development
API key · HTTPS reported · CORS Unknown
Sendgrid
A cloud-based SMTP provider that allows you to send emails without having to maintain email servers
API key · HTTPS reported · CORS Unknown
How to compare them
Coverage
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Operating cost
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Integration risk
Test auth, errors, pagination, latency, versioning, and outage behavior.
Data rights
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Source reference
This page separates source-reported facts from questions that need live provider verification.