Flat textfile help?

[KeithSum]

<?php 
echo "<title>Good bye: $fEmail</title>";
$fEmail = @$_POST["email"]; 

$values = "$fEmail\r\n";  

$fp = @fopen("email.data", "w") or die("Couldn't open the file for writing!"); 
$numBytes = @fwrite($fp, $values) or die("Couldn't write values to file!"); 

@fclose($fp); 
echo "Your E-Mail has been scheduled for removal. Thank you."; 

?> 

The above code was designed to write emails to a text file so my users can unsubscribe from the mailer.
It works kinda... hehe What the problem is it only writes one email to the file the from there on out
it just over writes the email!

What I need it to do is:

email.data contents:

[e-mail]
[e-mail]
[e-mail]

One email per line and no way to overwrite eachother.

Thanks in advance!

-K

[Installer]

About using the "w" switch with fopen, the manual says:

Open for writing only; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.

Concerning the "a" switch, it says

Open for writing only; place the file pointer at the end of the file. If the file does not exist, attempt to create it.

[bradgrafelman]

"... and truncate the file to zero length." -- Means delete any data after the internal pointer, effectively replacing all data you had before with the new data you've written.