I would like to create a marketing list from emails on another board

Hi Guys,

I have a leads board that I have emails in one column and a checkbox column,

I would like to create a list of emails where the checkbox is checked so that I can build a marketing email list, this list should be able to keep up with the checkbox and remove itself from the list if the checkbox is unchecked.

It would seem that this is not easy to achieve, any advice on how I might do this would be great.