I have VBA code samples to load templates and change the Sender address without going into Outlook's convoluted Template dialog but wanted a PowerShell version.
Use PowerShell to Delete Attachments
How to use PowerShell to delete large attachments from all messages in a classic Outlook folder or all attachments from selected messages in any classic Outlook folder.
Open Outlook Folders using PowerShell or VBScript
How to use PowerShell or VBScript scripts to open an Outlook for Windows folder.