Preservation according to the law (better defined as digital preservation of electronic documents) is the legal/electronic process regulated by Italian law that allows to create electronic documents with full legal value. Electronic storage puts paper documents on the same level as electronic documents, allowing private companies and public administrations to eliminate or reduce costs linked to printing, storage, filing, stamp duty for stamped journals, etc.
Preserving documents digitally means replacing paper documents (which by law some legal entities are required to preserve) with the equivalent document in digital format that is “blocked” in form, content and time using digital signature and timestamping.
The ever-increasing bulk of documents produced, with the need to give them the proper civil and tax value, has given rise over the years to a progressive updating of the Italian regulatory scene regarding electronic storage.
Below is list of some, but not all, of the documents that can be preserved digitally (electronic storage):

• Invoices
• Transport documents
• Tax receipts
• Till receipts
• Financial statements (balance sheet, income statement, explanatory notes, report on operations, reports of the statutory auditors and auditing firm)
• Tax returns
• Payment forms (e.g. Italian tax return forms F23 and F24)
• Audit records (e.g. daybook, VAT books, ledgers, inventory book, etc.)
• Single employment ledger
• Italian CUD form
• Offers
• Contracts
• Correspondence
• Shareholders’ register
• Debenture register
• Book of meetings and resolutions
• Health documents
• Registered documents generated by public administrations or companies subject to information registration
• Payment orders and collection vouchers

For some types of documents, electronic storage is the only legally valid storage method because by nature these types of documents cannot be materialized on paper. Below is list of examples (including, but not limited to):

• Certified Electronic Mail messages and receipts
• PA invoice
• Digitally signed contracts

Electronic documents that are made by scanning paper documents are sent to the law-compliant eWitness Preservation System via cryptographic router and Secure VPN.
The files/documents transmitted by the client via VPN are stored on an FTP server (pro FTPD). 
The FTP server has the peculiarity of generating a series of records of the operations that have been carried out. 
The first record is the HASH code of the document, included in a signed PDF, which is delivered to the client as receipt.
In addition to the files, the client may also send a series of metadata that can be helpful, for example, for a document system that extracts the metadata used for documentary purposes.
The system that manages the documents generates the log and metalog files at the end of the day. 
The notary takes responsibility for the deposited documents, freezes them after affixing his/her signature and certifies the existence of the documents entrusted (the signatures produced by eWitness are in the ETSI – PADES format) on a certain date.