Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
When using Scoutbook to send a message, there is an inbox and deleted option. Both options are always empty. No matter how many messages I send through Scoutbook.
So each time I send a message there is no record of it, and each time someone responds there is no record of it. All responses go directly to my email.
I set up a filter in my email account to send all emails sent from Scoutbook to a “Sent from Scoutbook” Label(Gmail) so that they don’t show in my inbox. This way I have a sent folder for Scoutbook that I can refer to anytime. You just have to be sure you have selected yourself when sending the email in Scoutbook to receive a copy. Replies to the email come to my Gmail inbox.