格式化电子邮件中的文本

Sorry, still a novice but getting better. I'm building a website and because I'm not that good I'm providing a page where club members can report problems and give me enough information to look into it. I have written the PHP code to send me an e-mail. If I echo the $message it prints fine on the screen but in an e-mail it's just one long sentence with the HTML tags in it. I searched for a solution and tried the ""Content-type: text/plain; charset=UTF-8"" but that did nothing. I know I'll be embarrassed when I get the answer but I am stuck. Thanks in advance.

<?php  
//  Convert form data to srting data

    $first_name=$_POST['first_name'];
    $last_name=$_POST['last_name'];
    $e_mail=$_POST['e_mail'];
    $browser=$_POST['browser'];
    $browser_version=$_POST['browser_version'];
    $os=$_POST['os'];
    $os_ver=$_POST['os_ver'];
    $device=$_POST['device'];
    $make=$_POST['make'];
    $issue=$_POST['issue'];

//  Use string data to create and send e-mail

    $to = '*******@*****.com';  //  will need to be converted to webmaster@stjoesclub.com
    $subject = 'Problem with St. Joseph Web Site';
    $message = $first_name . " " . $last_name . " is reporting a problem with the web site. <br><br>" .
               "E-mail address:  " . $e_mail . "<br><br>" .
               "Browser:  " . $browser . "<br>" .
               "Browser Version:  " . $browser_version . "<br><br>" .
               "Operating System:  " . $os . "<br>" .
               "Operating System Version:  " . $os_ver . "<br><br>" .
               "Device:       " . $device . "<br>" .
               "Device Make:   " . $make . "<br><br>" .
               $issue;


//  Send e-mail to webmaster

    mail($to, $subject, $message, 'From: ' . $e_mail, "Content-type: text/plain; charset=UTF-8");

?>

use Content-Type as text/html as below

$eol="
";

# Common Headers
$headers = "Message-ID: <".time()."-".$e_mail.">".$eol;
$headers .= "X-Mailer: PHP v".phpversion().$eol;                      
// These two to help avoid spam-filters

# Boundry for marking the split & Multitype Headers
$headers .= 'MIME-Version: 1.0'.$eol;
$headers .= "Content-Type: text/html; charset=iso-8859-1".$eol.$eol;

mail($to, $subject, $message, 'From: ' . $e_mail, $headers);

Content-Type should be set to text/html as said by @Ben Fortune

Eureka! Thanks to the help from Harish Singh I was able to solve my own issue. Looking at his code one problem I found was that the string $mailHtml was undefined which was the reason for a blank e-mail.

But learning from his code I figured out the $eol stood for End Of Line. By using that instead of the

the e-mail formats correctly when it comes in via the e-mail.

Unfortunately it doesn't work if I echo the $message on the screen after submission but fortunately I saved the old code so I can print it properly. I know that's not effective code but for a rookie hack it works.

Thanks again for the help.