Sales email subject "&" turns to  

[rbncha]

Preconditions

PHP 7.0.1
Mysql 5.6.31
Apache 2.4.23
Magento 2.0.7/2.1.0/2.1.1

Steps to reproduce

1. Admin > Stores > General > General > Store Information > Store Name : change store name something having ampersand "&" like Easy&Piggy
2. Send an order email.

Expected result

1. Order email subjected: Your Easy&Piggy order confirmation

Actual result

1. Your Easy&Piggy order confirmation (& is converted to &)
2. 

[veloraven]

@rbncha thank you for your report.
Could you please add some formatting to the last line? As I see "& is converted to &" instead of "& is converted to &" and it's confusing.
You can just add "" sign before &

[quienti]

Probably same problem, but with mail subject where ' is '
Add '' do not works.
On Magento 2.1.1

[olysenko]

Hi,
internal ticket is created MAGETWO-58663

[calvintwr]

any updates on this issue? i see that this issue has no assignment.

[PieterCappelle]

Quick fix is in di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Email\Model\Template">
        <plugin name="mail_subject" type="VENDOR\MODULE\Plugin\Template" sortOrder="100" />
    </type>
</config>

In Template.php

namespace VENDOR\MODULE\Plugin;

class Template
{
    public function afterGetSubject(
        \Magento\Email\Model\Template $subject,
        $result
    ) {
        return htmlspecialchars_decode((string)$result, ENT_QUOTES);
    }
}