Connection request email and system private message email: eliminate the latter

When a member requests a connection with another member they receive 2 emails: one is 'Notifications at [sitename] that gives details about the user that is requesting to connect and includes links to profile and connection management, while the other is a message that simply indicates that there is a new private message from "system".

How can we eliminate this System message?

We can find the matching string in the language file and if we delete the value then the messages stop, but we are concerned that other messages based on the same language string will be negatively impacted, but we have no idea where or when those messages might be generated.

When a member requests a connection, we only want the requested member to receive the "Notifications at [sitename]" email and not the System email.

Within CB > Configuration > Connections set "Notification Method" to "Email" so they are only emailed. Alternative is to turn off PMS email notifications, but that will impact all private messages.