Unable to send email in outlook Microsoft

Question

Delivery has failed to these recipients or groups:

This message couldn't be delivered because the sending email address was not recognized as a valid sender. The most common reason for this error is that the email address is, or was, suspected of sending spam. Contact the organization's email admin for help and give them this error message.

Answer 1

Hi @Pragnya Vojjala

Welcome to our forum!

Based on your description, your email address may have been flagged for spam.

Here are a few steps you can take to resolve this issue:

• Contact your organization's email administrator. They can check if your email address has been blocked and help remove any restrictions.
• Check the content of your message. Certain keywords or phrases in the email may trigger spam filters.
• Contact the recipient to add your email address to their safe senders list. This helps prevent your emails from being marked as spam.

Also, to reduce the possibility of spamming, please refer to the tips in this article:

10 tips on how to help reduce spam.

---

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

---

Answer 2

resolution from Microsoft:

https://learn.microsoft.com/en-us/defender-office-365/outbound-spam-restore-restricted-users