How to retrieve original print files in EngageOne Vault

This is achievable using e2util, which is provided as part of the standard Vault installation.

This is detailed in the Vault Customizing Guide, and achieved using the -d switch:

-d: manually decompresses a file.

Example:
E:\Demo\Exjourn\server>e2util.exe -d
download\110102-085022-TelcoStatement.xml.drp
09:18:35 e2 Vault Utility 5.4M2p0076
09:18:35 (C) Copyright 2009 Pitney Bowes Software Inc.
09:18:35 e2 Vault Utility licenced to [ABC Company]
09:18:35 decompressing
[download\110102-085022-TelcoStatement.xml.drp]
09:18:39 [download\110102-085022-TelcoStatement.xml.afp]
decompressed

You should note that any AFP retrieved will not contain any resources as these are always stripped out of the AFP on ingestion.