You may find that some messages do not appear in the searches that are performed in Email Track and Trace.
Email Security.cloud
The domain is currently registered as a 'Third Party Domain.' At this time, traffic from third party domains is not logged in Track and Trace. Please note that Track and Trace only supports domains registered under 'My Domains.
If the email is sent via a third-party application like SendGrid, the email address might change for each recipient.
Example: bounces+2657320-d828-firstname.lastname=example.com@em1004.example.com
Replace the text with * to narrow the search in Track and Trace = *@*.example.com