Hi @DundiAkhil-3404,
Agree with michev.
If you send emails to internal Office 365 email addresses, these messages will show up in the message trace.
If you use SMTP relay to send emails to external email addresses, these emails only use an Office 365 email addresses as the from address and could not go through Office 365 EOP (Exchange online Protection), so they would not be searched in a message trace. Like michev said, you need to resort to other external tools.
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