We should authenticate MailChimp account before using it. This tool is very sensitive and they are very restricted about spamming and sending bulk emails using wrong methods. So you should authenticate your account first. For it, you need to verify your domain and use SFP and DKIM records in your cPanel.
The effective digital marketing tool is email. Through emails, we can share our product or service's information easily. But sometimes during online marketing when we create newsletters or campaigns, required different email marketing tools.