Enable email previews to be turned on or off

[aschey]

As a KSF developer, I would like to be able to dynamically enable or disable email previews. Email previews should be off by default and should be able to be enabled using an environment variable.

Acceptance Criteria

• Email previews are disabled if the environment variable does not exist or is not set to 1
• Email previews are enabled if the environment variable exists and is set to 1

[sowmya20189]

Need help from the tech lead