You can not use Thunderbird, Mailbird, or Microsoft Outlook INSTEAD of gmail, they are email clients (well outlook.com is an email service but that is not what you are describing). And MailChimp is something entirely different again, neither Email Client nor end user email service. Not sure what exactly are you trying to say with the article in the end then?
Written by Sigmund Brandstaetter CISSP, CCSP, CISM, OSCP, CEH
With a total of 30 years in the IT Industry, I have focused on Cybersecurity (Services) and related skills over the past 15 years,