Unfortunately not possible on either macOS Mail nor iOS/iPadOS Mail. It’s been a frustration for me for years. Therefore, I use Mail as an email reader and then

Unfortunately not possible on either macOS Mail nor iOS/iPadOS Mail. It’s been a frustration for me for years. Therefore, I use Mail as an email reader and then switch over to Fastmail when I need to reply to something. Admittedly, I despise email so this switching of apps isn’t too bothersome for me (I rarely ever have to compose email) but it still would be nice if Apple enhanced Mail with this feature.