//头像重置到 i.leixue.com (last update 2018/11/12)
add_filter( 'get_avatar' , 'my_custom_avatar' , 1 , 5 );
function my_custom_avatar( $avatar, $id_or_email, $size, $default, $alt) {
	if (filter_var($id_or_email, FILTER_VALIDATE_EMAIL)) {//判断是否为邮箱
		$email = $id_or_email;//用户邮箱
		$user = get_user_by( 'email', $email );//通过邮箱查询用户信息
	}else{
		$uid = (int) $id_or_email;//获取用户 ID
		$user = get_user_by( 'id', $uid );//通过 ID 查询用户信息
	}
 
	//$user_login = $user->user_login;//用户名
	$email = $user->user_email;//用户邮箱
	$alt = $user->user_nicename;//用户昵称
	if(get_comment_author_email( $comment )){//通过评论获取邮箱
		$email = get_comment_author_email( $comment );
		$alt = get_comment_author( $comment );
	}
 
    $avatar = "https://i.leixue.com/avatar.php?email=".$email;
    $avatar = "<img alt='{$alt}' src='{$avatar}' class='avatar avatar-{$size} photo' height='{$size}' width='{$size}' />";
 
    return $avatar;
}