You can archive your Email attachments to a Microsoft SharePoint folder by making one of your SharePoint folders your Default App Folder. This requires that you determine the SharePoint folder location. Do this as follows:
Go to Microsoft SharePoint.
Select a SharePoint site and optionally a folder within that site.
Create an Excel workbook in the SharePoint folder.
Open your existing AppSheet application in the AppSheet Editor.
Go to the Data > Tables tab and click Add New Table.
In the GET DATA FROM dialog, select your Microsoft provider.
Select "SharePoint".
Browse to your SharePoint site and folder.
Select the Excel workbook you added earlier.
Go to the Table > Data tab.
Select your newly added table.
Expand Storage.
Copy the entire first part of the Source Id property. This value starts with "SHAREPOINT_SITE_ID". If you specified a folder, include the folder name. Omit the worksheet file name.
You can now delete the newly added table. All of the preceding steps were present to obtain the "SHAREPOINT_SITE_ID" value from the previous step.
Go to the Info > Properties tab.
Expand APP PROPERTIES
Copy the "SHAREPOINT_SITE_ID" value into the Default app folder property.