E04001 — AttachmentContentTypeBlocked
The attachment content type is not allowed. See the email attachment documentation for the blocklist.
- HTTP status: 422
- Type: validation_error
- Name: AttachmentContentTypeBlocked
What to do
The request body parsed, but one or more values are invalid. Read the details array: each entry names the failing field (param, a dotted path like to[0].email) with a human-readable reason. Fix the named fields and retry.
Related
- E04xxx — Email sending & delivery: every code in this range
- Errors: the full wire contract, status mapping, and error catalog
- Error handling: branching on type and code, validation details, and vendor_code