copy sent mail to sent folder

OS is Windows Server 2025. PS version is 5.1.17763.9121

I have been using a PS script for will over a year now to send an e-mail letting me know when a server backup successfully completes, and when it fails. I now have a need for emails sent using PowerShell to also be copied to the sent folder when sent. I've searched all over MS and other powershell support sites, and the best I can find deals with saving items in a shared mailbox folder. I'm not using a shared mailbox. I'm sending the e-mail from a comcast.com e-mail address. Where can I find guidance on doing what I need? For reference if it helps, the last line in my scripts that actually send the e-mail is below. 

$SMTPClient.Send($SMTPMessage)