Email Notifications are not sent to specific agent even though they are associated to that department

Email Notifications are not sent to specific agent even though they are associated to that department

Hi,

We have an agent who has admin access and is associated to multiple departments. 

We have enabled notification via email to all department members when ever a new ticket is added/created to that department. 

However, all user gets the notification email except one user. Not sure why.

Please guide on resolving the same.

Suggest if you need any further information