area: email
action: adddomain
https://api.hypermail.com/api.php?apikey=YOURAPIKEYHERE&area=email&action=adddomain&domain=test.com&usercontrolled=1
<response>
<success>Domain Added</success>
<id>111</id>
</response>
{
"success": "Domain Added",
"id": "111"
}