正在分析包含垃圾字符的电子邮件地址

我通过我编码的表单发送电子邮件，出于某种原因，在某些情况下，电子邮件地址会变成垃圾邮件，而在其他情况下，它可以正常工作。

//on form page
$message = str_replace("@e",$emtemail,$message);

$message存储在SQL中（在另一个页面上定义），$emtemail也是如此$消息只是发送的电子邮件的主体，我将用人们发送付款的电子邮件替换@e的所有实例。它向客户发送一封电子邮件，向我发送一封邮件。

//customer e-mail
//the display address might appear as payment52.62gmail.com instead of payment@gmail.com
//my e-mail
//all e-mail addresses formatted properly without error, @ appears as @

为什么电子邮件地址解析奇怪？与编码有关？

这就是我所掌握的所有与发送电子邮件相关的代码。我无法准确指出问题所在。

//any variables used in the below but not declared are previously initialized
$em = $userc["email"];
$subject = $emailone["subject"];
$subject = str_replace("@o",$ordernum,$subject);
$subject = str_replace("@u",htmlspecialchars($rn),$subject);
$subject = str_replace("@g",$gt,$subject);
$subject = str_replace("@sl","www.SZVapor.com",$subject);
$subject = str_replace("@ss","SZVapor.com",$subject);
$subject = str_replace("@st","SZVapor",$subject);
$message = nl2br($emailone["message"]);
$message = str_replace("@o",$ordernum,$message);
$message = str_replace("@u",htmlspecialchars($rn),$message);
$message = str_replace("@t",$table,$message);
$message = str_replace("@e",$emtemail,$message);
$message = str_replace("@g",$gt,$message);
$message = str_replace("@a",$addrsubmit,$message);
$message = str_replace("@sl","www.SZVapor.com",$message);
$message = str_replace("@ss","SZVapor.com",$message);
$message = str_replace("@st","SZVapor",$message);
$message = str_replace("@c",$em,$message);
$headers = "MIME-Version: 1.0"."'r'n";
$headers .= "Content-type: text/html; charset=iso-8859-1"."'r'n";
$headers .= "From: no-reply@SZVapor.com";
mail($em, $subject, $message, $headers);

给出的一些电子邮件地址示例：

payment62.44gmail.com
payment54.45gmail.com
payment22.59gmail.com
payment25.49gmail.com