WordPress 判断邮箱是否设置了头像，做一下记录，下面有代码出处。

function validate_gravatar($email) {
    // Craft a potential url and test its headers
    $hash = md5(strtolower(trim($email)));
    $uri = 'http://www.gravatar.com/avatar/' . $hash . '?d=404';
    $headers = @get_headers($uri);
    if (!preg_match("|200|", $headers[0])) {
        $has_valid_avatar = FALSE;
    } else {
        $has_valid_avatar = TRUE;
    }
    return $has_valid_avatar;
}

代码出处：https://stackoverflow.com/questions/32755354/check-if-a-user-has-a-gravatar-wordpress