There are a couple of ways to determine if this change affects your organization. For example, when you use a cloud service platform to relay emails through Exchange Online, the SMTP envelope sender domain (P1 sender domain) will be the 3 rd party service’s domain (perhaps for bounce tracking), but the SMTP header domain (P2 sender domain) is your organization’s domain.Ĭheck if your organization is affected by this change You use a third-party cloud service to relay messages by creating an Inbound Connector of OnPremises type.Your organization uses an application hosted on-premises to send email and the SMTP envelope sender domain (P1 sender domain) is not an accepted domain in 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 domain.

Your organization hosts email on-premises, and you need to relay non-delivery reports (NDRs) generated by your on-premises system through Exchange Online.

Possible scenarios that are affected by this change include, but may not be limited to: This change may affect your organization’s email routing or delivery.

The sending host’s IP address or certificate domain on the SMTP connection matches your organization’s Inbound Connector of OnPremises type.Īfter 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.

SMTP envelope sender domain in the MAIL FROM command (P1 sender domain).

After we remove this condition, relaying email through Exchange Online will require the following: On November 1, 2023, we are removing the matching condition for the SMTP P2 sender domain (1c above).

The sending host’s IP address or the certificate domain on the SMTP connection matches your tenant’s Inbound Connector of OnPremises type.

SMTP header sender domain, as shown in email clients (P2 sender domain).

SMTP envelope sender domain in the MAIL FROM command (P1 sender domain) or.

SMTP certificate domain on the SMTP connection or.

Any of the following is an accepted domain of your organization:.

If your organization does not use Inbound Connectors of OnPremises type then this change will not affect you.Ĭurrently, to relay email through Exchange Online, two conditions must be true: Today, we are announcing an update to our requirements for SMTP relay through Exchange Online.

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