How to always show a Bcc field in Mail I'm trying to send a message in Mail, but I don't have a Bcc field.

How can I show a Bcc field? Is there a way to set it as default, i.e. always show a Bcc field?
For the version of Mail.app included in El Capitan (checked 10.11.5), there is a very nice button dropdown close by:



The setting is maintained across emails and restarts.