If the former, I usually use Send In Blue. They have a new name but SIB will still come up in a search. Last I checked, they allowed 200 +/- free sends per day.
Otherwise, MailChimp, Hubspot, all the usual subjects. Frankly, I wouldn't worry about branding less and keeping the emails simple so they're easy to read on mobile, still have value when the email client blocks images, etc. Emails are about the receiver, not the sender :)