Starting Monday, I have had numerous clients using McAfee Email Security report rejected emails that state:
550 Validating Sender: bosauthsmtp17: Host ipaddress: No unauthenticated relaying permitted
550 5.7.0 Relay Access Denied
These are all emails that they've been able to email in the past. All rejections are coming from: MAILER-DAEMON@p01c12o148.mxlogic.net.
Sometimes, they can resend and it goes through, and for some, they cannot. I beleive this is part of the System Change over the weekend. I will be opening a support ticket.
The errors you noted in your post, while delivered by our servers () are not issued by our servers. I hope you were able to get additional information via your support request!
System Support Specialist
SaaS Email and Web Security
McAfee.Part of Intel Security.