Custom headers

How it works

Add application headers to outgoing mail. Pass a headers object with your send request. Use it for identifiers or your own unsubscribe integration.

Example

{"headers":{"X-Entity-Ref-ID":"order-123"}}

Things to know

At most 50 headers are allowed. You cannot override transport or MIME fields that SES builds. Header bytes count toward the 900,000-byte content limit. Transactional sends do not automatically generate unsubscribe headers.