“Fail” LED=550 5.7.136 RESOLVER.RST.SenderNotAuth
enticatedF orRecipien t; authentication required; Delivery restriction check failed because the sender was not authenticated when sending to this recipient.
In this post i will go over the option of removing the setting “Require that all senders are authenticated“.
In Exchange 2013 this can be removed by logging into the Admin Console > Recipients then select the mail contact and click edit. Remove the option “Require that all senders are authenticated”
However in Exchange 2016 this option is not available in the Admin Console and this needs to be done via Exchange PowerShell.
For this Example i will set the “RequireSenderAuthentionEnabled” to false on a Mail Contact.
Set-MailContact shaun -RequireSenderAuthenticationEnabled:$false