How to Send Email with PHPMailer over SMTP

PHPMailer SMTP settings

Step-by-step setup

1. Buy an SMTP package on the Bulko SMTP Relay page and copy the username and password from Dashboard -> SMTP Access.
2. Install PHPMailer with composer require phpmailer/phpmailer and load vendor/autoload.php.
3. Expose the credentials as environment variables SMTP_USERNAME and SMTP_PASSWORD (web server, PHP-FPM pool config or your framework's .env loader) and read them with getenv().
4. Create new PHPMailer(true) so errors throw exceptions, call isSMTP(), then set Host, SMTPAuth = true, Username and Password.
5. Match encryption to the port. PHPMailer::ENCRYPTION_STARTTLS (the string tls) goes with 587 or 2525. PHPMailer::ENCRYPTION_SMTPS (the string ssl) goes with 465. Mixing them is the most common PHPMailer SMTP error.
6. Call setFrom() with an address on your own domain. For aligned SPF, DKIM and DMARC, verify the domain under Sending Domains in the Bulko dashboard.
7. Set the content (Subject, Body, AltBody) and call send() inside try, printing $mail->ErrorInfo on failure.

Shared hosting sometimes blocks outbound 587 and 465. In that case keep ENCRYPTION_STARTTLS and set Port = 2525. More detail in the SMTP ports guide.

send-test.php

<?php
// send-test.php  (composer require phpmailer/phpmailer)
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;

require __DIR__ . '/vendor/autoload.php';

$mail = new PHPMailer(true); // true = throw exceptions on errors

try {
    // $mail->SMTPDebug = SMTP::DEBUG_SERVER; // uncomment to print the SMTP dialogue
    $mail->isSMTP();
    $mail->Host       = 'smtp.bulko.io';
    $mail->SMTPAuth   = true;
    $mail->Username   = getenv('SMTP_USERNAME');
    $mail->Password   = getenv('SMTP_PASSWORD');
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS; // 587 or 2525
    $mail->Port       = 587;
    // Port 465 instead:
    // $mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
    // $mail->Port       = 465;

    $mail->CharSet = PHPMailer::CHARSET_UTF8;
    $mail->setFrom('[email protected]', 'Your App');
    $mail->addAddress('[email protected]');
    $mail->Subject = 'PHPMailer SMTP test';
    $mail->isHTML(true);
    $mail->Body    = '<p>It works.</p>';
    $mail->AltBody = 'It works.';

    $mail->send();
    echo "Message sent\n";
} catch (Exception $e) {
    echo "Message could not be sent. Mailer Error: {$mail->ErrorInfo}\n";
}

Send a test email

Run SMTP_USERNAME=smtp_xxx SMTP_PASSWORD=yourpass php send-test.php from the command line with a real recipient in addAddress(). Message sent means the relay accepted the message; check the inbox within a minute or two.

If it fails, uncomment $mail->SMTPDebug = SMTP::DEBUG_SERVER; and run again. The output shows every SMTP command and reply, so you can see whether the problem is the connection, the TLS handshake, authentication (535) or content (554 5.7.1). Turn debug off again before going to production.

Troubleshooting

FAQ

Should SMTPSecure be tls or ssl in PHPMailer?

Use PHPMailer::ENCRYPTION_STARTTLS (tls) with port 587 or 2525, and PHPMailer::ENCRYPTION_SMTPS (ssl) with port 465. The constants are clearer than the raw strings.

Why use PHPMailer instead of PHP mail()?

mail() hands the message to the local sendmail with no SMTP authentication, so it often lands in spam or is blocked by the host. PHPMailer authenticates to a real SMTP relay.

Can PHPMailer read incoming email from this server?

No. Bulko SMTP is outgoing only, with no IMAP or inbox. Replies go to the From or Reply-To address you set.

Is there a sending limit?

The default is 2,000 emails per day per SMTP account. Contact [email protected] to raise it.

How much does it cost?

One-time packages: $5 for 5,000 emails, $15 for 20,000, $30 for 50,000, $60 for 150,000. Unused emails never expire and there is no free SMTP trial.