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The Mailer Component

5.0 version

The Mailer Component

The Mailer component helps sending emails.

If you’re using the Symfony Framework, read the Symfony Framework Mailer documentation.


$ composer require symfony/mailer


If you install this component outside of a Symfony application, you must require the vendor/autoload.php file in your code to enable the class autoloading mechanism provided by Composer. Read this article for more details.


The Mailer component has two main classes: a Transport and the Mailer itself:

use Symfony\Component\Mailer\Mailer;
use Symfony\Component\Mailer\Transport\Smtp\EsmtpTransport;

$transport = new EsmtpTransport('localhost');
$mailer = new Mailer($transport);

The $email object is created via the Mime component.


The only transport that comes pre-installed is SMTP.

Below is the list of other popular providers with built-in support:

Service Install with
Amazon SES composer require symfony/amazon-mailer
Gmail composer require symfony/google-mailer
MailChimp composer require symfony/mailchimp-mailer
Mailgun composer require symfony/mailgun-mailer
Postmark composer require symfony/postmark-mailer
SendGrid composer require symfony/sendgrid-mailer

For example, suppose you want to use Google’s Gmail SMTP server. First, install it:

$ composer require symfony/google-mailer

Then, use the SMTP Gmail transport:

use Symfony\Component\Mailer\Bridge\Google\Transport\GmailSmtpTransport;
use Symfony\Component\Mailer\Mailer;

$transport = new GmailSmtpTransport('user', 'pass');
$mailer = new Mailer($transport);

Each provider provides up to 3 transports: standard SMTP, HTTP (it uses the provider’s API but the body is created by the mailer component), API (it uses the full API of the provider with no control over the body creation – features might be limited as well).

The mailer component provides a convenient way to create a transport from a DSN:

use Symfony\Component\Mailer\Transport;

$transport = Transport::fromDsn($dsn);

Where $dsn depends on the provider you want to use. For plain SMTP, use smtp://user:pass@example.com or sendmail+smtp://default to use the sendmail binary. To disable the transport, use null://null.

For third-party providers, refer to the following table:

Amazon SES ses+smtp://ACCESS_KEY:SECRET_KEY@default ses+https://ACCESS_KEY:SECRET_KEY@default ses+api://ACCESS_KEY:SECRET_KEY@default
Google Gmail gmail+smtp://USERNAME:PASSWORD@default n/a n/a
Mailchimp Mandrill mandrill+smtp://USERNAME:PASSWORD@default mandrill+https://KEY@default mandrill+api://KEY@default
Mailgun mailgun+smtp://USERNAME:PASSWORD@default mailgun+https://KEY:DOMAIN@default mailgun+api://KEY:DOMAIN@default
Postmark postmark+smtp://ID:ID@default n/a postmark+api://KEY@default
Sendgrid sendgrid+smtp://apikey:KEY@default n/a sendgrid+api://KEY@default


If your credentials contain special characters, you must URL-encode them. For example, the DSN ses+smtp://ABC1234:abc+12/345@default should be configured as ses+smtp://ABC1234:abc%2B12%2F345@default

Instead of choosing a specific protocol, you can also let Symfony pick the best one by omitting it from the scheme: for instance, mailgun://KEY:DOMAIN@default is equivalent to mailgun+https://KEY:DOMAIN@default.

If you want to override the default host for a provider (to debug an issue using a service like requestbin.com), change default by your host:

mailgun+https://KEY:[email protected]
mailgun+https://KEY:[email protected]:99

Note that the protocol is always HTTPs and cannot be changed.

High Availability

Symfony’s mailer supports high availability via a technique called “failover” to ensure that emails are sent even if one mailer server fails .

A failover transport is configured with two or more transports and the failover keyword:

$dsn = 'failover(postmark+api://[email protected] sendgrid+smtp://[email protected])';

The mailer will start using the first transport. If the sending fails, the mailer won’t retry it with the other transports, but it will switch to the next transport automatically for the following deliveries.

Load Balancing

Symfony’s mailer supports load balancing via a technique called “round-robin” to distribute the mailing workload across multiple transports .

A round-robin transport is configured with two or more transports and the roundrobin keyword:

$dsn = 'roundrobin(postmark+api://[email protected] sendgrid+smtp://[email protected])'

The mailer will start using the first transport and if it fails, it will retry the same delivery with the next transports until one of them succeeds (or until all of them fail).

Sending emails asynchronously

If you want to send emails asynchronously, install the Messenger component.

$ composer require symfony/messenger

Then, instantiate and pass a MessageBus as a second argument to Mailer:

use Symfony\Component\Mailer\Envelope;
use Symfony\Component\Mailer\Mailer;
use Symfony\Component\Mailer\Messenger\MessageHandler;
use Symfony\Component\Mailer\Messenger\SendEmailMessage;
use Symfony\Component\Mailer\Transport;
use Symfony\Component\Messenger\Handler\HandlersLocator;
use Symfony\Component\Messenger\MessageBus;
use Symfony\Component\Messenger\Middleware\HandleMessageMiddleware;
use Symfony\Component\Mime\Address;

$dsn = 'change-dsn-accordingly';

$transport = Transport::fromDsn($dsn);
$handler = new MessageHandler($transport);

$bus = new MessageBus([
    new HandleMessageMiddleware(new HandlersLocator([
        SendEmailMessage::class => [$handler],

$mailer = new Mailer($transport, $bus);

// you can pass an optional Envelope
$mailer->send($email, new Envelope(
    new Address('[email protected]'),
        new Address('[email protected]'),

Learn More

To learn more about how to use the mailer component, refer to the Symfony Framework Mailer documentation.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.