One of our users doesn't want to receive the "This task was assigned to

No this is happening for some set of users only, Ok Let me explain you one scenario, Lets a Say User a is created in our Env, using an Admin PM , where after creating a user we are using the Edit Alert Settings For User SS where the parameters are
Alert: New Task Assigned to Me
Disable: True
Media: Email
User:pv!userCreated
Once this node is completed we are trying to add the user a into respected Groups which are related to his access (like we have 4 applications in 1 server so we need to restrict them to show only the specified application). After this we are assigning this User a one Task, lets say TaskDisplayName is : Task 123456,Then a Mail is received by the User where New Task: Task 123456 and body of the Mail contains the priority and the task link, which the user a doesn't want it. Some of the users are not getting it , is there any way to figure this out.

No this is happening for some set of users only, Ok Let me explain you one scenario, Lets a Say User a is created in our Env, using an Admin PM , where after creating a user we are using the Edit Alert Settings For User SS where the parameters are
Alert: New Task Assigned to Me
Disable: True
Media: Email
User:pv!userCreated
Once this node is completed we are trying to add the user a into respected Groups which are related to his access (like we have 4 applications in 1 server so we need to restrict them to show only the specified application). After this we are assigning this User a one Task, lets say TaskDisplayName is : Task 123456,Then a Mail is received by the User where New Task: Task 123456 and body of the Mail contains the priority and the task link, which the user a doesn't want it. Some of the users are not getting it , is there any way to figure this out.