//This works
$working_header = "MIME-Version: 1.0\n" .
	"Content-Type: multipart/alternative;\n" . 
	"           boundary=\"" . $mime_boundary . "\""; 

//This doesn't
$not_working_header = "From: info@mydomain.net\n " . 
	"MIME-Version: 1.0\n" .
	"Content-Type: multipart/alternative;\n" . 
	"           boundary=\"" . $mime_boundary . "\""; 


//This works
mail($_SESSION['email'], $welcsubject, $welcbody, $working_header);


//This doesn't
mail($_SESSION['email'], $welcsubject, $welcbody, $not_working_header);


Why?!