Whitelisted IP lets emails send with bad username and password

On testing server and a copy of the live site for development purposes emails were still being sent out from the plugin through Sendgrid account (the correct account) even though we tried to prevent emails being sent by changing the username and password setting in the plugin. The server is whitelisted for the account and perhaps this is what lets it go through. We were simply trying to keep the client from being spammed with e-commerce purchase notifications while worked on new features. Plugin let every single email go through even though we had invalid data in the settings. Not a big bug but certainly odd.