bob@smith.com, 2010-01-10
bob@smith.com, 2010-02-10
bob@smith.com, 2010-03-10
bob@smith.com, 2010-04-10
ronda@q.com, 1984-01-02
ronda@q.com, 1990-04-02
ronda@q.com, 1996-08-02
want above data to appear as
bob@smith.com, 2010-01-10, 2010-02-10, 2010-03-10, 2010-03-10
ronda@q.com, 1989-01-02, 2010-04-10, 1984-01-02, 1990-04-02, 1996-08-02