validation_error - Email SDK

The message, route, schedule, capability, or adapter-specific input is invalid before dispatch.

EmailValidationError has code validation_error and is not retryable.

It covers missing required message fields, invalid attachment sources, invalid zoned timestamps, incompatible fallback fields, repeated headers on incapable adapters, recipient/tag limits, duplicate adapter/plugin names, invalid retry counts, and other synchronous configuration errors.

Fix the input or client construction. Retrying unchanged data cannot succeed.

src/validate.ts

await email.validate(message, options);

Use public validate or CLI send --dry-run to reproduce this class without sending.