(Existing mac os mail feature). There are scary stories about people accidently putting external recipients on CC of [top scret] internal emails. Also, never want to send confidential customer info to a wrong person because of autosuggestion typo for CCed name.

I'd like to configure recepient names colors in Composer by domain. Say, use blue for colleagues from my company, red for customer A, green for customer B and, say, brown for all other recipients. Being able to visually check the recipients removes a big part of email anxiety!