Returns the metadata of a logged email: the entity it is linked to, subject, sender, To/Cc/Bcc recipients, plain-text body, attachments (as document references) and the sizes of the stored EML and HTML files. Use the EML and HTML download-link operations to get the full message.

The record is looked up within the caller's tenant, and the caller must also be allowed to access the entity the email is linked to (employer, customer, lead, workflow or meeting, checked in that order); otherwise that entity's access check rejects the request.

Errors: 400 if id is missing or not a UUID; 404 if the record does not exist in the caller's tenant.