You may be able to set up a reroute from your old email to your new email.
If not maybe set an "out of office" message saying you have moved.
You dont say if you have changed ISP and are setting up an email with them.
If so then I would say DONT, and set up an email which is ISP independant, like say Googlemail.
Then if you change ISP in the future you dont need to tell everyone your email address has changed again.