JSON with PHP 8.0

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JSON

Drupal 9 and higher require PHP compiled with JSON. JSON support is normally compiled as part of PHP core, but in case you’re getting errors like PHP Fatal error: Call to undefined function Drupal\\Component\\Serialization\\json_encode() in ... core/lib/Drupal/Component/Serialization/Json.php try adding the JSON extension.

So it is installed on default no need to install additional php packages

For Email I have no idea.