When testing a production app we occasionally need to pull from a live site and perform tests on a development server. There are quite a few email addresses stored in the database that we need to modify every time we restore to the development server. Occasionally someone on my team will miss one and accidentally send an email through the distribution list. The email looks legit because it is coming from a clone, it can cause quite the situation. We have a protocol we follow every time we clone the live app and it has helped a lot but I would feel better if it was impossible for the two servers to communicate. Is there a good way to do this? Can firewall rules block email? Does Plesk have a blacklist?