How to share sensitive files securely with clients (without email)

Why email attachments are the wrong default An attachment is a permanent copy you cannot recall. It lands in mail servers, backups and the recipient's client, it is readable by whoever runs those systems, and autocomplete regularly sends it to the wrong person. Consumer transfer services solve the size problem and add a provider who can read the file.

The method, in six steps

1. Put the document in an encrypted space. It should be ciphertext before it leaves your machine, so no intermediate system ever holds a readable copy.

2. Create one link per recipient. Never one link for a group: attribution and revocation both depend on separation.

3. Set an expiry that matches the purpose. A review window is days, not indefinitely. Add a view budget for particularly sensitive material.

4. Add a passphrase and send it on another channel. Link by email, passphrase by phone or SMS. Interception of one channel then yields nothing.

5. Choose view-only with watermark when appropriate. For material that must be read rather than kept, per-viewer watermarking discourages redistribution and identifies the source.

6. Revoke when the purpose ends. Closing a matter should include revoking its links. Expiry handles the ones you forget.

Making it easy for a non-technical client Tell them exactly what will happen: "You will receive a link by email and a code by text. Open the link, type the code, and the document opens in your browser. There is nothing to install and no account to create." That sentence removes most support calls.

What to do about very large files Use a tool with chunked, resumable uploads and verification after upload. A 4 GB transfer that fails at 90% is the reason people fall back to consumer services, which is the reason confidential files end up somewhere you cannot control.

Keep a record of the disclosure For each send, you want: who, what, when created, when first opened, when it expires or was revoked. An append-only audit trail gives you that automatically, and it is the artefact you will want if handling is ever questioned.

The one habit that matters most Make the secure path the fastest path. If sending a protected link takes three clicks and attaching a file takes two, people will attach the file. Choose tooling accordingly, and set it as the default in your templates and email signatures so clients expect it.