Most of my filters are simple searches. And if you can search, you can apply it retroactively. Also FastMail’s search works for any email header so it can be m

Most of my filters are simple searches. And if you can search, you can apply it retroactively. Also FastMail’s search works for any email header so it can be more potent than that of Gmail. I wonder why can’t they add a checkbox to apply the rules retroactively. Seems to be simple enough.