Occasionally Microsoft requires account holders to add or verifiy account recovery methods, such as security questions, phone numbers, and verification email accounts. When that happens, mail delivery to apps may stop.
Please log in at https://portal.microsoft.com to see if this is the issue, and to set up the required information. None of the information provided is visible to SEARK College. In addition, this information will be necessary to use the system's password reset functionality at https://passwordreset.microsoft.com.
If this is not the issue, please contact the helpdesk.