Using throw in C#

I am building an ASP.NET MVC application, and I am trying to find a way where I can collect  custom error messages if any and send  them back to the view.We have a employee class with id, firstname,lastname and designation properties  and  have a crew manager class with list of employees (IEnumarable) and other properties in it.I have following code that loops through each employee in crewmanager class and  calls ValidateMethod1 and throws custom error message to UI for any particlular employee .This code is working fine without any issue .But now I want to collect error messages for all the employees in crewmanager class and then send to UI. For example Suppose if  I have 10 employess in crewmanager  and below condition is satisfied for 7 employees it should send all the  7 employee's error messages (List) to UI. How can I  acheive this with below code?

foreach (var emp in CrewManager.Employees)
{
    ValidateMethod1(emp.id);
}

 Void ValidateMethod1(emp.id)
  {
        if(condition)
        {
            throw new CustomException("Exception with parameter employee '{0}', emp.id)
        }
 }

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