The SMTP relay access denied issue is an email error occurring when the sender fails to authenticate the outgoing mail server. The error may also occur if the recipient has marked your server as spam. When the error occurs, it doesn’t allow your email to be sent from your mail server to the recipient’s. The error occurs showing, “554 5.7.1 Relay access denied” message.Proceed with steps given below to fix the SMTP relay access denied issue.
Fixing SMTP Relay access denied in Outlook: