Common provider-independent message shape accepted by ctx.mail.send(...).
provider is validated for the configured SMTP vendor and translated into
approved MIME headers. It is not an arbitrary provider API payload and
cannot override addressing, content, authentication, or transport settings.
Common provider-independent message shape accepted by
ctx.mail.send(...).provideris validated for the configured SMTP vendor and translated into approved MIME headers. It is not an arbitrary provider API payload and cannot override addressing, content, authentication, or transport settings.