The common reasons as follows:

• Email has been categorized as spam  -  Please check your spam folder.
• Blocked unknown senders  -  If your email will block unknown senders, please add "[email protected]" to your email whitelist.
• Dispatched to a folder by the inbox rules / filters  -  If you are using inbox rules (/filters) to categorize all your emails, please check all folders (include the trash can).