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This error occurs.....
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Hi
Thanks for posting your question in the Microsoft Q&A forum.
Based on your description, I would like to know the following information to resolve this issue:
2.Can you provide the full NDR?
Thank you for your response
We implemented the empty return-path directly within our own application that sends out emails. This is handled programmatically in our email sending logic, not through a mail flow rule in Office 365.
" We implemented the empty return-path directly within our own application that sends out emails." indicate that you have your own application. It seems to be related to Exchange Development. To better solve your question, I will add the Exchange Development tag.
How specifically are you sending these?
I just tested with a hybrid SMTP connector and an empty return path <> worked fine.
Thank you for your response Andy. Could you provide more details on how you configured the hybrid SMTP connector to successfully use an empty return path? I am encountering issues with my current setup and would greatly appreciate any specific settings or configurations you applied.
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Yes, I simply telneted to Exchange 2016 and entered the MAIL FROM: <> and the FROM as a real email address and sent to an Exchange Online mailbox. It was delivered intact. The connector is certificated based
Thanks for your advice Andy! I tried something similar, but I'm emailing to external places like Hotmail and Gmail.., and it’s not working the same way.
Do you have any tips for sending emails to other email services that might help?
Thank you!
Yea that error is def a Microsoft one https://learn.microsoft.com/en-us/exchange/troubleshoot/email-delivery/ndr/relay-access-denied-smtp
Are you sure your connector is configured correctly per that article?
Thanks for the link Andy. I checked our connector settings, and everything looks right. But I'm still having trouble with emails that don't have a return path.
Do you have any other ideas on what I can try? Or is there something specific I should look for that might show why these emails aren't working?
Thanks for any more help you can give!