Sends an email template to each mission's consignee, on demand. templateId is optional: name one and it is used for every mission in the batch, or leave it out and each mission gets the enabled End of visit template its own notification configuration points at, falling back to the account's default End of visit template when no template covers that configuration. A null, empty or blank templateId is read as leaving it out, not as an id to look up. Any ENABLED email template in the account may be named, whatever its trigger mode, so a template set to Manual - and therefore never sent automatically - is still reachable here. A disabled template is rejected with a validation error, whether it was named or resolved. Mission ids must be unique; a repeated id is rejected with a validation error rather than emailing the same consignee twice. Each submitted mission is evaluated on its own and gets its own entry in the response, in submission order: one mission failing never stops the others. An outcome of SENT means the message was accepted for sending, not that it was delivered; the delivery outcome stays visible in the back office's sent-email list, where every send made through this endpoint is recorded as API-triggered.