About the SMTP class and an example

Because of the display, there are some spaces in the post that have been removed, causing some errors to be used.
The analysis is as follows:
1, because of inadvertently modified, we get such a very good class, always want to change to look comfortable. But I need to be reminded that in this program, sometimes adding or removing several spaces can cause a program error.
2, now I will send up a number of procedures to explain some of the issues.
Content-type: There are several spaces in front of the next 1-2 lines. Please Add. The spaces in front of each line in the HTML are not displayed, so there is nothing in the post.
This is a friend of the previous post of content, I modified as follows:
This is a multi-part message in MIME format.
--=====_1__=====
content-type:multipart/alternative;
boundary= "=====_2__====="
--=====_2__=====
Content-type:text/plain;
charset= "GB2312"
Content-transfer-encoding:base64
x+vkudpd1qez1khutuwguphkvbxe08q8/sjtvp7atllpv7s4w9pkvp4=
--=====_2__=====
content-type:text/html;
charset= "GB2312"
Content-transfer-encoding:base64
pgh0bww+pghlywq+pc9ozwfkpjxib2r5pjxomt7a/dftpc9omt48l2jvzhk+pc9odg1spg==
--=====_2__=====--
--=====_1__=====--
Here's an example:
Actually, it's very simple.
$sender = new SMTP ();
$fromname = "Sony";
$frommail = "sonymusic@china.com";
$toname = "Pbabi";
$tomail = "Panbei@163.net";
$subject = "an example";
$text _body= "Please use the HTML-enabled mail software to view the message";
$html _body.= "$send _ok= $sender->send ($fromname, $toname, $frommail, $tomail, $subject, $text _body, $html _body);