I'd like to have a piece of outgoing mail to a recipient who already has a label without using the "apply label" button. I tried creating a filter that has a "to" and "from" to apply a label, and that didn't work.
As the user Eddie has stated, filters can only be applied to incoming mail, not outgoing mail. A filter is designed to filer content that you more or less have no control over. An outgoing message on the other hand is user generated, and therefore is already in your control, so there is no need to normally filter these.