Hybrid Mail flow : unable to send emails to external receipents

pavan kumar 371 Reputation points
2021-04-20T17:53:41.89+00:00

Hi,

we have a hybrid setup, everything is working fine, but the emails from office 365 mailbox to external receipents is coming with the relay access denied and showing our domain.com name in the NDR. we have a hybrid setup with the centralized mail flow enabled.

Thanks
Pavan.

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  1. Lucas Liu-MSFT 6,161 Reputation points
    2021-04-23T07:39:01.1+00:00

    Hi @pavan kumar ,
    1.Does your firewall set an outbound policy? Because the current phenomenon is that the outgoing mail fails. If possible, please try to temporarily turn off the firewall and send a test email.

    2.Will this error occur when you send mail to other external recipients? Based on the error message, I think it is impossible to judge that it must be an error on your side. If only a specific user has this error, please try to send it to that user using another email address.

    3.Please make sure that your DNS records are set up correctly, especially SPF records. In addition, if you can, you can also confirm that the other party's DNS record settings are correct. Please refer to: MXToolBox
    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    4.Please check the connectors in the "Mail flow" in Office 365 Exchange admin center.By default, there are only two connectors created by HCW. Have you created the others? Please check the send connectors in the "Mail flow" in on-premises Exchange server. Please make sure that the send connector you created to send mail to the Internet is configured correctly.


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