Each lead that you create will be assigned a unique id known as the maildrop id which look will like - 2bsxsaua.b28gaxxn@maildrop.clinchpad.com.
All email communications will automatically get added to the lead by either keeping the maildrop id in CC/BCC from your email acount or forwarding the mails to the assigned maildrop id of that lead.
To integrate your email account using maildrop click on the lead in the Pipeline view.
Select the Emails option from the lead details page and retrieve your maildrop id.
All email communications will automatically get added to the lead by either keeping the maildrop id in CC/BCC or forwarding the mails to the maildrop id.