Reference
Sending-only API keys limited to send endpoints
API keys with the sending scope can now only send, reschedule, cancel, retry and forward emails. Reading emails and other resources needs a full access key.
Updated Sep 27, 2026
Sending-only keys could previously list and retrieve emails and call some other read endpoints. They’re now limited to Send an email and the actions on an existing email: reschedule, cancel, retry and forward. Other endpoints reject sending keys.
If your integration also reads emails, domains or other resources, use a full access key for those calls. See API keys.