We deal with queries such as missing emails on a case-by-case basis. Please open a new support request with one of our team and provide as much pertinent information as possible. If you received a bounce message please include that with the support request. Otherwise we will need the sending email address, the recipient’s email address as well as the date and time that the mail was sent in order to trace what happened to the mail.
If you are a 365 / Exchange Online user, you can login to the Exchange Online Admin interface and perform a search and discovery of the missing message yourself.
Dcentral, our self-serivce control panel, will in future also provide functionality to trace email delivery.