Auto update distribution list Exchange 2003

Hi’

I have a question that I hope you can help me with.
I have a lot of contacts in severel different distribution lists.
When a contact’s email address changed, it would suggest that the change would be reflected in the distribution lists instantly. But that is not the case.
I realize that you can press the ‘Update now’ button, but then you will of course have to open the distribution list.
I’m looking for a solution that can update the distribution lists automatically.
I am running with exchange 2003