I have setup my first MailChimp account but I ran into trouble reading their CAPTCHA.
It was simply stated “Impossible to decode” !

MailChimp – login page when wrong password is wrongly filled too many times : Captcha unreadable, UI issues
Unfortunately my experience with MailChimp was quite bad as I had to refresh several times the CAPTCHA I had to decode.
Conclusion
I like the post “Why You Should Stop Using CAPTCHAs” written by Oskar Smith stating the following: “we accept [the CAPTCHA] as an unavoidable step in the battle against bots and spam. But what if it was shown that CAPTCHA codes are not only damaging the usability of your website, but also hampering the ability of your site to create leads, generate sales or otherwise function and interact with your audience?“
I think that MailChimp goes definitely in the wrong direction….