Button to load emails in a textbox

Hi all. I have a contacts list with emails and specific tags from all of them.

I want to create a button that copies all the emails in a selected tag, separated with ; for Outlook in a textbox to have it for send an email from another button that copies these emails into the BBC.

For example, if I select the Tag "Delegados" (is a Selection field) in the textbox only will copy the emails that have these tag.

Thanks