Symfony

Before you start

• PHP 8.1 or later
• symfony/mailer

1Install the mailer

Skip this if the component is already there.

composer require symfony/mailer

2Point the DSN at the sandbox

# .env.local
MAILER_DSN=smtp://mc_0000000000000000:pw_0000000000000000@smtp.mailclutch.com:587

Keep it in .env.local rather than .env: the credentials are per environment, and that file is not committed.

3Send a test message

php bin/console mailer:test anyone@example.com

Or from your own code:

use Symfony\Component\Mime\Email;

$email = (new Email())
    ->from('staging@example.com')
    ->to('anyone@example.com')
    ->subject('Sandbox check')
    ->text('Hello from Symfony.');

$mailer->send($email);

Watch it land

Open the sandbox and the message is there — rendered HTML, plain text, raw source, attachments, and the SPF, DKIM and DMARC verdicts. It updates live, so you can leave it open next to your terminal.

Nothing is ever delivered onward, whatever address you send to; claim the inbox with an account and it stays.

What usually goes wrong

• Messenger holds the message

  If framework.messenger routes SendEmailMessage to a transport, mail leaves only when a consumer runs: php bin/console messenger:consume async.

• Special characters in the DSN

  The username and password are URL-encoded inside the DSN. Ours are base32, so nothing needs escaping — but a hand-written password with @ or / does.

Other stacks

The same four values in another dialect. Every guide below is filled in with the sandbox pair at the top of this page.