Email not in sent mailbox

We have attestation process for users. The mailbox from which the email is going is email@domain.com. Also cc'd on the notification to user is email@domain.com. When an email is sent out it is not seen in the sent mail on the email@domain.com mailbox. When we trigger the user attestation manually, we see it in sent mailbox. Please advise what could be missing

Thanks,

Sri