Integration with MailChimp
This is a Premium feature. Please make sure you have integrated with MailChimp successfully. Here is a step-by-step guide for you on the integration.
MailChimp Double Opt-in
Have not you seen them under the MailChimp account?
If so, it could be caused by “Enabled MailChimp Double Opt-in” option.
When this option is enabled, after the emails were pushed to MailChimp, MailChimp will send another email to these emails with an approval button. These pushed emails would not display under your MailChimp account until the end customers click the approval button in the emails.
Therefore, if you want, you could try to uncheck the double opt-in option, then the emails should show up under the MailChimp account after the auto sync.