Hyperlinks not showing up in Yahoo - PHP Mail Function

Question

I currently am running a site where students can buy and sell books to each other for my college. Its www.books4csusm.com. The past few days I have been getting e-mails where people are unable to delete their book.

After submitting their books they are sent an e-mail using PHP mail function and it displays their books along with a link to the right of the title to delete it.

It works for me on gmail(and it doesnt work for other people that use gmail, very weird) but I just tried it in yahoo and it looks like a link but you can't click it. At first I was using books4csusm@gmail.com to send the e-mail.

Then I did some research and found out that I should use an e-mail that corresponds to my domain so now I am using support@books4csusm.com

I am stuck and have no idea and I keep on getting e-mails from users asking if I can delete their book.

http://i.imgur.com/ErA1fqc.png

It is showing up as a link but when you click it nothing happens. When I inspect element this is what it shows.

 <a id="yui_3_7_2_1_1377788967568_2506" rel="nofollow">
  Delete Book
</a>

No idea what to do

function send_book_email($email, $post_id, $name)
{
    $to = $email;
    $subject = "$name , Your Book(s) have been Submitted!";
    $message = "Hello $name,<br><br>Thank you for using www.books4csusm.com. <strong>Please do not delete this e-mail.</strong><br><br>";
    $message .= "<strong>Title</strong><br>";

    $book_id = get_book_id($post_id);
    while($row = mysqli_fetch_array($book_id))
        {
            $message .=  "" . $row['title'] . " - <a href='www.books4csusm.com/remove_new.php?PostID=" . $post_id . "&BookID=" . $row['bookID'] . "'>Delete Book</a><br>";
        }
        $message .= "<br><br>To delete your book Select the Delete book above of the corresponding book.<br>";
        $message .= "<br><br>Don't forget to like us on Facebook <a href='https://www.facebook.com/Books4Csusm'>https://www.facebook.com/Books4Csusm</a><br><br>BOOKS4CSUSM";

       $from = "support@books4csusm.com";
       $headers  = 'MIME-Version: 1.0' . "\r\n";
       $headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
       $headers .= "From:" . $from;
       mail($to, $subject, $message, $headers);
 }

Answer 1

I figured it out though and it was so simple that I overlooked it. I added the

 http:// to the www.books4csusm.com/remove_new 

and now it works. It does not show up as spam in yahoo and I can now delete the books that i have poseted.

Answer 2

Just use http:// before adding your domain to the variable or link.

No spam is reason or not needed any settings.

Just Put http:// in your url and you are done

$url="www.example.com"; // Is Wrong in php mailer for yahoo

$url="http://example.com/"; // it will work in yahoo.in gmail.

But you should test it with Outlook also.