email flow Ex2013 to Ex2007

Hi,

I have below enviroment where I am not able to send email from Ex2013 box "Users" to Ex2007 box "users" or even Exchange 2013 "Users" are not able to send email themself.  all emails are going into queue

1 DC 2003 SP2

1 Exchange 2007 with all roles on single server

1 Exchange 2013 with all roles are on single server.