Exchange 2016: Allow anonymous relay (5.7.54 Unable to Relay)
Some applications or devices require an anonymous relay to be able to send mails. However, a distinction must be made here between internal relay and external relay. The internal relay, i.e. the anonymous sending of mails to the domains accepted by Exchange, works out-of-the-box: The external relay, i.e. the sending of mails to external users without authentication, however ... Read more