Emails being bounced

Question

I am trying to send an email to the below address and it keeps getting bounced regardless of whether I send it from my cell phone, laptop or desktop or my work email address. I have confirmed the accuracy of the email address. Any help would be of assistance. Here is the notification;

******@tc.gc.ca
Remote Server returned '550 5.7.134 RESOLVER.RST.SenderNotAuthenticatedForMailbox; authentication required; Delivery restriction check failed because the sender was not authenticated when sending to this mailbox'

Answer 1

Hello PaulMcNairn,

Welcome to Microsoft Community and appreciate your time taken for sharing detailed information. I understand that the problem is not being able to send mail to a certain email address and getting a bounce error message. If my understanding is wrong, please correct me in the reply. I am glad to offer you help on this issue.

According to your description, you have tried several methods to send the mail, but all of them are bounced. This is not your problem, but the recipient refused to accept the document. Messages you send are bounced when the recipient is a mailbox configured to reject messages from external senders outside your organization or from senders outside your organization.

For your problem, you can refer to the solution given in this link, which may solve your problem.

We need to go through a series of steps to find the real cause of the problem. If the above steps do not solve your problem, please let me know and I will continue to assist you with the problem.

Best Regards,

Mavis - MSFT | Microsoft Community Support Specialist

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