i am using exchange 2016 hybrid environment. I have an application which is using a service account saccount1 to trigger email to an unified group group1. when the service account triggers email from the application, in the logs i can see the error is 550 5.7.60 SMTP; Client does not have permissions to send as this sender"
Under unified group1-Group Delegation- the service account has Send As and Send on Behalf permissions. the service account has office 365 license.. I am using my onprem relay i.e mrfa.mydomain.com on port 587. Shoud i use smtp.office365.com on port 587. service account is an onprem account and which is in sync with azure AD and has a remote mailbox. experts guide me