If you didn't want to send HTML to the mail client, you could always just use tabs. To get php to insert a tab use \t. Something like this:
<?
$body = "name:\t\tShirley Wilson\n";
$body = $body . "organization: \tWest High School";
mail("somebody@abc.com", "Subject", "$body");
?>
This example inserts two tabs after name:, because organization would probably span at least 1 tab. If that makes sense. Here's an example of what it would output (view source to see the raw text): http://gagon.net/test/tabs.php
This would be quicker and easier than outputting HTML, but you would have much more control with HTML (colors, font sizes, etc).
Hope this helps!