OnChange insert Date

Hi all

Just a little help please...

I have created a very simple database to capture marketing data.

I have a form which is linked to a table. On the form are fields such as, company name, contact name and Email address. The Email Address field is always blank and needs to be populated when we identify what it is.

Another field is [Date Changed], which its default is also blank (format date/time).

Could you please advise what code I should add to the Event/OnChange to the [Email Address] field so that when the field is changed, the Now() data will be inserted in the [Date Changed] field?

Thanks
Gary