Update 11/13/2023: We added new information on how to know when this change is released to your organization.
Today, we are announcing an update to our requirements for SMTP relay through Exchange ...
Updated Feb 22, 2024
Version 19.0
Blog Post
I have been following this article since it was originally posted, and am confused about the fix for this scenario -
1, Your organization hosts email on-premises, and you need to relay non-delivery reports (NDRs) generated by your on-premises system through Exchange Online. In this scenario, the NDRs often have null as the SMTP envelope sender (P1 sender), but the SMTP header sender domain (P2 sender domain) is your organization’s accepted domain in Microsoft 365.
All I see is the ability to report on it, which doesn't seem to work -
> Start-HistoricalSearch -EndDate "01/01/2024" -StartDate "01/17/2024" -ReportTitle "Report all emails using non accepted domains as the sender" -ReportType "P2SenderAttribution" -NotifyAddress ######
Write-ErrorMessage : |Microsoft.Exchange.Management.Tasks.ValidationException|Invalid notification address or notification address not in accepted domains.
Either way, in most Hybrid environments shouldn't the bulk of NDR's be sent from O365, if the domains are authoratative in the tenant where the recipients exist, and if a NDR needs to be sent, it would go to the originator which would be an accepted domain, and so technically not relaying?