New in Symfony 7.2: Mime Improvements

November 5, 2024 • Published by Javier Eguiluz

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The Mime component provides tools to create and manipulate MIME messages. In Symfony 7.2, we introduced new features to improve it.

Custom MIME Encoders

Contributed by Kai Dederichs in #54975

The MIME standard was created to extend the original format of email messages to support text in character sets other than ASCII, as well as attachments of any type. In Symfony's Mime component, this is possible in part thanks to the encoders used by TextPart elements. Previously, the encoders were a hardcoded list (quoted-printable, base64, 8bit).

In Symfony 7.2, TextPart items allow you to define custom encoders for your specific needs. For example, if your app uses SOAP Attachments, you'll need to create a custom encoder like this:

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        use Symfony\Component\Mime\Encoder\ContentEncoderInterface;

class MyEncoder implements ContentEncoderInterface
{
    public function encodeByteStream($stream, int $maxLineLength = 0): iterable
    {
        // ...
    }

    public function encodeString(string $string, ?string $charset = 'utf-8', int $firstLineOffset = 0, int $maxLineLength = 0): string
    {
        // ...
    }

    public function getName(): string
    {
        return 'my_encoder';
    }
}
    

Now, you can use this encoder in your TextPart items when creating the MIME message:

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        // ...
TextPart::addEncoder(new MyEncoder());
$content = new TextPart('...', 'utf-8', 'plain', 'my_encoder');
    

Unicode Email Addresses Support

Contributed by Arnt Gulbrandsen in #58361

Traditionally, email addresses only allowed ASCII characters in both the local part and the domain part. This was inconvenient for a large part of the world's population, so RFC 6531 introduced an extension to the SMTP protocol to support internationalized email addresses.

In Symfony 7.2, we're adding support for Unicode characters in both the local and domain parts of email addresses:

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        use Symfony\Component\Mime\Email;

$email = (new Email())
    ->from('jânë.dœ@ëxãmplę.com')
    // ...
    

You don't need to change anything in your application to use this feature. If the remote SMTP server doesn't support Unicode email addresses, you'll see an InvalidArgumentException with an error message explaining the issue.

Published in #Living on the edge

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Comments

Loick Piera said on Nov 5, 2024 at 10:59

Nice improvements 👏.

I'm just curious that adding content encoder interface requires a method getName() and that a name is also needed when calling TextPart::addEncoder. Is that really intended?

I also found it strange to use aliases when everywhere else we are now encouraged to use FQCN directly 😁

Javier Eguiluz Certified said on Nov 5, 2024 at 12:06

About requiring to pass the encoder name, we changed that in https://github.com/symfony/symfony/pull/58764

We also updated the blog post and now the addEncoder() method only requires passing the encoder object.

Christophe Coevoet said on Nov 5, 2024 at 12:36

@Loick Piera the name of the content encoder actually appears as part of the mime message, in the Content-Encoding header. It is not just an internal alias of the Symfony project. So using the FQCN is not an option here

Loick Piera said on Nov 5, 2024 at 13:53

Alright, thanks @Javier for the changes and @Christophe for the explanation. It's all good then 🎉