using System;

using System.Collections.Generic;

using System.Linq;

//using System.Collections.Generic.CollectionExtensions;

​

public class Program

{

    public record Account(string ownerEmail, string acc, string svc);

    public static void Main()

    {

        var rows = new List<Account>{

            new Account("a@m.com", "acc1", "svc1"),

            new Account("a@m.com", "acc1", "svc1"),

            new Account("a@m.com", "acc2", "svc2"),

            new Account("b@m.com", "acc2", "svc2"),

            new Account("c@m.com", "acc3", "svc3")

        };

        var byEmail = rows.GroupBy(x => x.ownerEmail, x => x).Distinct();

        foreach (var email in byEmail)

        {

            foreach (var acc in email)

            {

                Console.WriteLine(email.Key + " " + acc);

            }

        }

    }

}