In der Function newsletterSubscribe in CustomerImporter.php muss
$sql = "INSERT INTO s_campaigns_mailaddresses (customer, groupID, email)
VALUES (1, {$customer['newslettergroupID']}, {$customer['email']});";
durch
$sql = 'INSERT INTO s_campaigns_mailaddresses (customer, groupID, email)
VALUES (1, ' . $customer['newslettergroupID'] . ',"' . $customer['email'] . '");';
ersetzt werden!!