Configure sendmail on 2 Linux redhat machine, one for generate mail, second to transmit to a relay

* An old linux machine A contains an application, that test hardware and sends report by email by using SendMail. The email are send to a relay at the headquarter (I don't have access). * A new linux machine B also make the same, and sends reports to the same relay. After the relay, the emails are sent to people internally, or suppliers externaly, ... The headquarter changes the relay to a new one. The machine B can still send email to the new relay. But the machine A cannot because TLS is too old and cannot talk to the new relay. Month after month all applications are transferred to B, but it will take 2 or 3 years. * Try1:install new TLS on old A... No, it doesn't work, too old generation. * Try2:sendmail A sends the results to B. And B sends its own email and also the emails from A. Question : how to configure SendMail on machines A and B to do this ? It seems no too complex, but there are no many parameters.. Today the only parameters are "local domain". Thanks for every useful start of solution :) J-Michel