UPDATE: I answered another question with a more elaborate tutorial of how to do this with jQuery .ajax()
: Adding subscribers to a list using Mailchimp's API v3
Looking at the Mailchimp documentation and assuming you have a given list in mind, it looks like you would call this endpoint with a GET:
/lists/{list_id}/members/{subscriber_hash}
To do this in PHP, I found a nice script sitting on github. Their last function would probably do the trick for you:
function mc_checklist($email, $debug, $apikey, $listid, $server) {
$userid = md5($email);
$auth = base64_encode( 'user:'. $apikey );
$data = array(
'apikey' => $apikey,
'email_address' => $email
);
$json_data = json_encode($data);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://'.$server.'.api.mailchimp.com/3.0/lists/'.$listid.'/members/' . $userid);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json',
'Authorization: Basic '. $auth));
curl_setopt($ch, CURLOPT_USERAGENT, 'PHP-MCAPI/2.0');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "GET");
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POSTFIELDS, $json_data);
$result = curl_exec($ch);
if ($debug) {
var_dump($result);
}
$json = json_decode($result);
echo $json->{'status'};
}
If that function doesn't work, the only wrapper I could find for the v3 library works in conjunction with Laravel - Mailchimp v3 API PHP wrapper.