CREATE TABLE audit_trail (
      old_email TEXT NOT NULL,
      new_email TEXT NOT NULL
);

INSERT INTO audit_trail(old_email, new_email)
  VALUES ('harold_gim@yahoo.com', 'hgimenez@hotmail.com'),
         ('hgimenez@hotmail.com', 'harold.gimenez@gmail.com'),
         ('harold.gimenez@gmail.com', 'harold@heroku.com'),
         ('foo@bar.com', 'bar@baz.com'),
         ('bar@baz.com', 'barbaz@gmail.com');

with iter2 as (
    with iter1 as (
        select old_email, new_email from audit_trail where old_email = 'harold_gim@yahoo.com'
        ) select a.old_email, a.new_email from audit_trail a join iter1 b on (a.old_email = b.new_email)
) select * from iter1 union iter2;

ERROR:  syntax error at or near "iter2" at character 264
STATEMENT:  with iter2 as (
        with iter1 as (
            select old_email, new_email from audit_trail where old_email = 'harold_gim@yahoo.com'
            ) select a.old_email, a.new_email from audit_trail a join iter1 b on (a.old_email = b.new_email)
    ) select * from iter1 union iter2;
ERROR:  syntax error at or near "iter2"
LINE 5: ) select * from iter1 union iter2;