How do I do mass mailings?

I am trying to mail to a list of people, using fgets() and a while loop. When I do the "mail($to,$subject,$msg)" in a while loop, it mails but the subject line is left blank and there is a line in the message that says "Subject: ...".
The subject shows up where it is supposed to when I don't use a while loop.

Here's how I do it....
$Mreply = ujludwig@yahoo.com;
$Mfrom = "Ulysses Ludwig";

$L_from_string = "From: " . $Mfrom . "<" . $Mreply . ">rnReply_to: " . $Mreply;
mail($L_emailaddress, $Msubject, $L_customMbody, $L_from_string);