I’m encountering an issue after configuring Office 365 for outbound email. When attempting to send an email from user@domain.com, I receive the following error:
“The server refused the sender address with error b’5.7.57 Client not authenticated to send mail. Error: 451 4.7.0 Temporary server error.”
It seems like there might be an authentication problem. Has anyone experienced this before or have suggestions on how to resolve it? Any help would be greatly appreciated!
Which version?