I've been using Mailchimp for over 3 years and it's become the bane of my existence. Zero flexibility when it comes to design, but to be honest that is the least of their problems. Bugs. every. single. day. completely dismissive and unhelpful customer service, when the website goes down, or stops working, or simply does absolutely insane stuff, they will gaslight you saying something on the lines of "ThAt Is NoT aN iSsue". We'll be looking for a replacement soon but to be honest I'm surprised people still use it, only explanation I can think of is them being way cheaper than competitors. If you're in need of a email marketing platform, do yourself a favour and look somewhere else :)