Why can't I copy an email address in the right bar?

Ii use ubuntu mint and can’t copy an email on in the right bar. This is highly annoying. Also it sometimes does and sometimes doesn’t recognise my phone which could be due to other issues but my computer does recognise my phone. I can’t simply drag a file in if the add file function doesn’t work. It’s a nice app but it has some bugs, way more than thunderbird.