This may be due to the frequency of email notifications settings set by your organisation. This setting can be amended by a member of the Support Team on request.
The frequency of email notifications can be set to weekly, daily or never. Please note, these emails are only sent if the user has not visited the Collaboration centre for a period of time.
For example, if your email notifications are set to weekly, and you visit the collaboration centre for new messages more often than once a week, you will not receive an email notifying you of unread collaboration centre messages.
Please contact the Support Team if you would like to amend the frequency of your email/overdue notifications.