text: Create table If Not Exists Person (Id int, Email varchar(255));
  Truncate table Person;
  insert into Person (Id, Email) values ('1', 'a@b.com');
  insert into Person (Id, Email) values ('2', 'c@d.com');
  insert into Person (Id, Email) values ('3', 'a@b.com');
  
  SELECT DISTINCT P1.Email
  FROM Person AS P1 JOIN Person AS P2
  WHERE P1.Id != P2.Id AND P1.Email = P2.Email
  