area: leads
action: addlead
https://api.hypermail.com/api.php?apikey=YOURAPIKEYHERE&area=leads&action=addlead&firstname=John&lastname=Smith&email=test@test.com
<response>
<leadid>1</leadid>
<success>Lead Added</success></response>
{
"leadid": "1",
"success": "Lead Added"
}