"foldered" adjective

I found a Wikipedia explanation of foldering that is more specific than what you have in mind (A communicates with B electronically, without a paper trail, by working in a shared gmail account, writing a draft email, which can be erased after it's been read).

It sounds as though that's not what you're looking for, but rather

to file

to arrange (papers, records, etc.) in convenient order for storage or reference (dictionary.com)

The adjective would be filed, e.g. See if the Houseman estate is filed under H, will you?

Foldered appears to be a word that is in use, mostly in a computing context and with an implication of ‘finished’.

“Folder members (also called foldered objects) -- objects that must be stored in a folder.”

“All items encapsulated and/or foldered Located center flat file storage in public area – “Accessions” drawer”

“iAssembly Author Include/Exclude Foldered Items”

“Note if using an SDK to generate the URL, v1 is automatically added to the URL by default for foldered images”

“Foldered Tasks”

“Foldered & Finished: Ora Mae Curry Papers”