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 Online. If your organization does not use Inbound Connectors of OnPremises type then this change will not affect you.
Currently, to relay email through Exchange Online, two conditions must be true:
On November 1, 2023, we are removing the matching condition for the SMTP P2 sender domain (1c above). After we remove this condition, relaying email through Exchange Online will require the following:
After November 1, 2023, if either of the above conditions are not met, the relay attempt from your on-premises environment to Exchange Online will be rejected.
This change may affect your organization’s email routing or delivery. Possible scenarios that are affected by this change include, but may not be limited to:
You can use the newly created extended report type to generate the report for your organization by running Start-HistoricalSearch, it will generate an extended report specific to this scenario, (see Start-HistoricalSearch documentation.) Some examples below. Replace the value of NotifyAddress below with your email admin email address.
Start-HistoricalSearch -EndDate "2023/09/22" -StartDate "2023/09/18" -ReportTitle "Report all emails using non accepted domains as the sender" -ReportType "P2SenderAttribution" -NotifyAddress firstname.lastname@example.org
Start-HistoricalSearch -EndDate "2023/09/22" -StartDate "2023/09/18" -ReportTitle "Report on emails using a specific sender domain (non accepted domain) as the sender" -ReportType "P2SenderAttribution" -NotifyAddress email@example.com -SenderAddress *@MyDomain.com
Please note that senderAddress must be an accepted domain of your organization.
Start-HistoricalSearch -EndDate "2023/09/22" -StartDate "2023/09/18" -ReportTitle "Report on emails for a recipient domain using non accepted domains as the sender" -ReportType "P2SenderAttribution" -NotifyAddress firstname.lastname@example.org -RecipientAddress *@mycustomer.com
Please note that RecipientAddress CAN contain any domain that your organization send emails to.
You can use Get-HistoricalSearch to report the status of the extended report job:
Get-HistoricalSearch -JobId xxxx (where the xxxx is the JobID.)
If the job result (ReportStatusDescription) is “Complete – No results found”, that means you organization is not impacted by the scenario.
To minimize the effects of this change before November 1, 2023:
How to know when this change will be available for your organization?
We will be notifying customers via Office 365 Message Center when this change is about to deploy into their respective rings, with a start and expected end time. The title for the message center post will be “Deployment time for Updated Requirements for SMTP Relay through Exchange Online”. If your organization has not received any notification yet, it is either not impacted by this change based on our report, or your organization is not a part of the next batch to get the feature deployed yet.
We will be updating this blog post (as well as posting in the Office 365 Message Center) when the entire deployment is completed, which currently is set to be by 3/31/2024.
Exchange Online Transport Team
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