Mass update email value

I would like to update all the email addresses in our test environment to a dummy email. Is there a simple way to mass update the email field for contacts?
I have tried workflows and the mass update function, but it seems not to work that way.
Any ideas what I should do?

Thanks for help!

From what I understand, text fields cannot be mass updated and the email address field is a text field.

You would need to customise include/MassUpdate.php to accommodate the field type.

Thanks for your reply,
I an not sure what “include/MassUpdate.php” is… Do you have any documentation that may help me, or any link that describes this?

It is a core file which if modified would not be upgrade safe, but you would need to make a change in that file to add the standard text field type to the list of field types supported by mass update.