Signup Forms

This article explains how to create a form on your website that allows a visitor to subscribe to a mailing list. We will assume that you only need two pieces of information: their name and email address. The examples provided, which are written in PHP, can be easily modified to accept more fields. Three types of mailing lists are demonstrated: a plain-text file, a CSV file, and a database.

The Form

First we will address the signup form. You can either create a new page dedicated to just the form, or the form can be inserted into an existing page.

It is useful to perform some validation of the form fields. Instead of blindly polluting your mailing list with invalid data, it is better to report the problem in a popup window. Insert the following code inside your <head> element:

Next, there is the form itself. The following code implements a form that has two fields: the subscriber's name and email address.

<form action="signup.php" method=post name="ourform" onsubmit="return validate();">
Your name:<br>
<input size=70 maxlength=80 name=name id=name autofocus><br>
Your email address:<br>
<input size=70 maxlength=80 name=email id=email><br>
<br>
<center><input class=button type=submit value=" Subscribe "></center>
</form>

These fields are submitted to a PHP script named "signup.php". The following three sections describe the contents of this script, depending on what type of mailing list you are using.

Plain Text Mailing List

If your mailing list is a simple, plain-text file with one email address per line, then the signup.php file looks like this:

<?php
$email = strtolower($_POST['email']);
$name = $_POST['name'];

// already subscribed?
$file = file_get_contents('c:\example\mailing list.txt');
$i = 0;
while(true) {
    $j = stripos($file, $email, $i);
    if($j===false)
        break;

    $ch = $file[$j - 1];
    if($ch=="\r" || $ch=="\n" || $ch=='<' || $j==0) {
        $ch = $file[$j + strlen($email)];
        if($ch=="\r" || $ch=="\n" || $ch=='>')
            die("You are already subscribed to this mailing list.");
        }

    $i = $j + strlen($email);
    }

// add new subscriber
$file = fopen('c:\example\mailing list.txt', 'a');
if(!$file)
    die("Error: failed to open mailing list.");

if($name=="")
    fwrite($file, $email . "\r\n");
else
    fwrite($file, "\"" . $name . "\" <" . $email . ">\r\n");

fclose($file);
echo "Your signup was successful. Thanks!";
?>

Replace both instances of "c:\example\mailing list.txt" with the filepath of your mailing list. Here is an example of how the file might look:

"Joe Schmoe" <joe@example.com>
nameless@example.com
"John Public" <john@example.com>

CSV Mailing List

If your mailing list is a CSV file, then the signup.php file looks like this:

<?php
$email = strtolower($_POST['email']);
$name = $_POST['name'];

// already subscribed? (assumes all cells are quoted)
$file = file_get_contents('c:\example\mailing list.csv');
if(stripos($file, '"' . $email . '"') != false)
    die("You are already subscribed to this mailing list.");

// open the file
$file = fopen('c:\example\mailing list.csv', 'a');
if(!$file)
    die("Error: failed to open mailing list.");

// if the file is new, write the column names on the first line
fseek($file, 0, SEEK_END);     // necessary due to a bug in fopen("a") and/or ftell()
if(ftell($file)==0)
    fwrite($file, "name,email\r\n");

// write the data record
fwrite($file, "\"" . $name . "\",\"" . $email . "\"\r\n");

fclose($file);
echo "Your signup was successful. Thanks!";
?>

Replace both instances of "c:\example\mailing list.csv" with the filepath of your mailing list. Here is an example of how the file might look:

name,email
"Joe Schmoe","joe@example.com"
"","nameless@example.com"
"John Public","john@example.com"

Database Mailing List

If your mailing list is in a database, you will need to install ODBC support into PHP. For Microsoft IIS, this can be done in IIS Manager > Sites > [your website] > PHP Manager > PHP Extensions > Enable or disable an extension. You must enable "php_pdo_odbc.dll".

The signup.php file looks like this:

<?php
$email = strtolower($_POST['email']);
$name = $_POST['name'];

// open the database
try {
    $db = new PDO("odbc:my_dsn", "my_user", "my_password");
}
catch(PDOException $e) {
    echo "Failed to open database.\r\n" . $e->getMessage();
    return;
    }

// already subscribed?
$sql = "SELECT my_email_column FROM my_table WHERE my_email_column LIKE '$email'";
foreach($db->query($sql) as $row) {
    if($email==strtolower($row['my_email_column']))
        die("You are already subscribed to this mailing list.");
    }

// add new subscriber
$sql = "INSERT INTO my_table (my_email_column, my_name_column) VALUES ('$email', '$name')";
if(!$db->query($sql)) {
    echo "<pre>Failed to add subscriber.\r\n";
    print_r($db->errorInfo());
    echo "</pre>";
    return;
    }

echo "Your signup was successful! Thanks!";
unset($db);
?>

Make the following replacements in the above script:

Replace This	With This
my_dsn	The name of the ODBC Data Source. This must be created in the ODBC Administrator under the "System DSN" tab.
my_user	The user name required for database authentication.
my_password	The password required for database authentication.
my_table	The name of the table that holds the mailing list.
my_email_column	The name of the column that holds the subscriber's email address.
my_name_column	The name of the column that holds the subscriber's name.

Gammadyne Mailer

It is possible to connect Gammadyne Mailer directly to the mailing list when it is located on another computer.

If the mailing list is a plain-text or CSV file, you can specify its URL in the Recipients File field on the Recipients branch. Normally this field expects a local filepath, but it will also accept a URL as of version 60.0

If the mailing list is a database, then you need to make sure the ODBC Data Source or Connection String (Gammadyne Mailer supports both methods) refers to the domain name or IP address of the server that hosts the database. The ODBC Data Source is configured in the Windows ODBC Data Source Administrator (choose "Register Database" from the Database menu). The ODBC Connection String is configured directly on the Database branch (click the Browse button next to this field).