Fake Repository Collection

using System.Collections.Generic;

namespace EmailNotificationSender
{
    class Customer
    {
        public string FirstName { get; set; }
        public string SecondName { get; set; }
        public string EmailAddress { get; set; }
    }

    class CustomerRepository
    {
        public IEnumerable<Customer> GetAll()
        {
            yield return new Customer
            {
                FirstName = "Sarah",
                SecondName = "Smith",
                EmailAddress = "ssmith@dontcodetired.com"
            };

            yield return new Customer
            {
                FirstName = "Gentry",
                SecondName = "Jones",
                EmailAddress = "jonesyg@dontcodetired.net"
            };

            yield return new Customer
            {
                FirstName = "Arnold",
                SecondName = "Day",
                EmailAddress = "daytimedontcodetired.net"
            };
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var repository = new CustomerRepository();
            var customers = repository.GetAll();
 
            foreach (var customer in customers)
            {
                // ... do something with each customer
            }

            Console.ReadLine();
        }
    }
}