drupal_mail() new line \n not working
Could be a couple things, without seeing any of your code it's difficult to help you.

Try: 


Making sure you're using double quotes (") instead of single quotes (') around the new line characters. (This is because PHP does not interpolate strings defined by single quotes).
Setting the Content-Type to text/plain in the mail headers. (If you need HTML in your email, use &lt;br /&gt; for new lines).


Also, you should always use \r\n with emails so the new line is recognized across all platforms.