CODEWITHSUNDEEP
phpemailpear
Russ
Russ

Reputation: 2006

Send email reliably and handle errors robustly

I'm making my first site for a learning exercise as I've been a java back-end developer. I am setting up a user registration form and since this is going to be my user's first glimpse at my site, I want to make sure I handle things as robustly as possible. Through some trials I've come across and implemented almost all these solutions:

At this point I have realized sending email reliably is not quite as trivial as I originally thought. My question is what is the most reliable way to send mail, and what is the most robust way to handle exceptions? For instance if SMTP is the most reliable way, please explain why and provide a simple example with error handling.

For any of the errors that occur, are they errors where doing some automated retry would benefit? I understand that just because I send mail doesn't mean the person will get it, but I'm asking what the most robust solution is because I'm sure other people have done this 100 times over.

To prove I'm not just a lazy coder, this is what I've got so far which has been working - but I have no idea how robust this actually is (pear mail):

<?php } else if ($_SERVER['REQUEST_METHOD'] == 'POST') {

    include('Mail.php');
    include('Mail/mime.php');

    $to = urldecode($_POST['email']);
    if (preg_match('(\r|\n)', $to)) {
        die('No email injection for you!');
    }

    $headers = array(
        'From'=>'tag <[email protected]>',
        'Subject'=>'Registration for mysite.com'
    );
    $text_body = 'boring text message';
    $html_body = '<html>
        <head><title>Welcome</title></head>
        <body>
            <p>slightly less boring message</p>
        </body>
    </html>';

    //Utilize the mime class to generate mime body and add mime headers
    $mime = new Mail_mime();
    $mime->setTXTBody($text_body);
    $mime->setHTMLBody($html_body);
    $body = $mime->get();
    $headers = $mime->headers($headers);

    //Utilize the mail class to send the mime mail
    $mail = Mail::factory('mail');
    $mail->send($to, $headers, $body);

    echo 'mail sent maybe?';
?>

EDIT: Code sample using SMTP with error handling

<?php } else if ($_SERVER['REQUEST_METHOD'] == 'POST') {

    include('Mail.php');
    include('Mail/mime.php');

    $to = $_POST['email'];
    $to = urldecode($to);
    if (preg_match('(\r|\n)', $to)) {
        die('No email injection for you!');
    }

    $headers = array(
            'From'=>'tag <[email protected]>',
            'Subject'=>'Registration for mysite.com'
            );
    $text_body = 'boring text message';
    $html_body = '<html>
        <head><title>Welcome</title></head>
        <body>
            <p>slightly less boring message</p>
        </body>
    </html>';

    //Utilize the mime class to generate mime body and add mime headers
    $mime = new Mail_mime();
    $mime->setTXTBody($text_body);
    $mime->setHTMLBody($html_body);
    $body = $mime->get();
    $headers = $mime->headers($headers);

    //Utilize the mail class to send the mime mail
    $host = 'mail.mysite.com';
    $port = '26';
    $username = '[email protected]';
    $password ='myPassword';

    $smtp = Mail::factory('smtp', array (
            'host' => $host,
            'port' => $port,
            'auth' => true,
            'username' => $username,
            'password' => $password
            ));
    $mail = $smtp->send($to, $headers, $body);

    if (PEAR::isError($mail)) {
        echo("<p>" . $mail->getMessage() . "</p>");
    } else {
        echo("<p>Message successfully sent!</p>");
    }
?>

Upvotes: 1

Views: 897

Answers (1)

cweiske
cweiske

Reputation: 31078

There are typically several steps involved in sending mail:

  1. Application: Put mail into queue of local delivery agent
  2. Delivery agent: Send mail to configured SMTP server
  3. SMTP server: Send mail to destination mail server
  4. User mail application: Fetch mail from mail server
  5. User: Click on mail, read it

PHP's mail() function puts the mail into the queue of the local mail delivery agent on unix. You'll only get an error (return value false) if that does not work. You do not get notified when the agent cannot deliver the mail further or any of the steps 2-5.

Using a direct SMTP connection to your SMTP server at least gives you an if the mail cannot be delivered to your SMTP server, which is more information than you get with mail(). What you don't get is information if the mail does not get read or is simply filtered out into a spam folder, or if the remote mail account does not exist (3-5).

To get to know that the remote account exists, you need to either parse the error response mails ("Undelivered mail returned to sender), or implement the full remote server SMTP connection and sending yourself (step 3), which I would not recommend.

To find out if the mail has been read, you could embed a "web bug", a tiny (potentially clear) image that is displayed in the HTML mail and notifies you that the mail has been displayed. You can use this to put sent mails into a database and mark them as read when your web bug image URL gets called. Mails that did not get read in X days can be seen as "not read" or "failed" - but the user can also simply be on vacation :)

Reliability & robustness

Your own mail server (step 3) automatically tries to re-send mails when the remote user's mail server is down. If that does not work, you'll get mails like "Mail delivery delayed for 24 hours", and another mail when it stopped doing that.

So once the mail is on your mail server, you can be sure that this server will do everything it can to deliver it.

Upvotes: 4

Related Questions