Next Mail is the easiest way to grab the subscribers by letting the visitors input their email . In order to add Next Mail services into your website, at first you have to go to the wordpress dashboard then just click plugins then press over add new.
Now you need to type ‘Themedev’ in the search box then the Next Mail plugin apears . After that just install and activate it.
Just click on the Next Mail’s general services then enable MailChimp. As an example you will get the MailChimp API key over there . you have to collect the key by clicking the link of ‘Get your API key here’. After going there you have to copy the API key and paste it into the ‘API key’s input field. Finally just save it.
At the very same way go to the Next Mail global services and enable popup. After that select the subscriber form and set up the popup mail position there then save it