Why does AWS Pinpoint show campaign to have emails sent but not delivered?

Question

I have setup a campaign with AWS Pinpoint where the receivers are part of a certain segment. I have gone through this process before and everything has worked fine but this time, even after a day the campaign metrics show that out of the total number of receives, all emails have been sent but none have been received.

Why is that? How can I fix that?

Example:

Answer 1

All the mail is quarantined. We need to release it manually. Mail does not appear in the mail box as it is blocked by Microsoft 365 Defender. Below is the link for your reference:[Find and release quarantined mail] 1

To open the Microsoft 365 Defender portal, go to https://security.microsoft.com. To go directly to the Quarantine page, use https://security.microsoft.com/quarantine.