Disable SparkPost mailer using a PHP constant

[mathieuhays]

I'm running the SparkPost plugin on a website I'm developping locally and then deploy to a production environment. My development environment include an email catcher that prevent emails to be sent by accident to the members of that website. My issue is that SparkPost bypasses that email catcher, probably due to the fact that the plugin is using HTTP instead of SMTP.

I usually disable the plugin locally but I do forget from time to time (when copying the production database locally to debug issues).

One solution would be to add a constant I can set on my local config that disables Sparkpost's mailer and fallbacks to WordPress' one.

example:

<?php // local-config.php

define('WPSP_DISABLE_MAILER', true);