Not receiving verification emails for SES identity verification.

I am trying to add and additional email address to our list of verified identities (for a domain that has already been verified and has two existing verified email addresses) and we never receive any verification emails. Can some advise how troubleshoot this issue. How can I confirm/change the email address verification emails are being sent to?

We have done a message trace on our O365 Exchange Admin console and checked logs on our cloud based spam filtering service and no relevant messages are being either received OR rejected by systems.