Thanks Nickler!
With MailChimp, the receivers would see the Unsubscribe link at the bottom, which clearly shows it's an automated email. Also, going through New list, New campaign workflows just for a quick email to 10-20 people is a little cumbersome.
Agreed with the automated emails. However, there are already solutions for this, and I wouldn't know how to differentiate it without a significant time investment.