Most small teams send sensitive information every day: invoices, payroll, ID documents, contracts, and reports. Most of it moves via email attachments and cloud links that nobody has really configured.

This guide gives you a simple, repeatable way to share client files safely — using the tools you already have — so you reduce the chance of data leaks, payment fraud, and GDPR trouble.

For a small team, one poorly shared file can be as damaging as a full-blown data breach:

An invoice or bank-detail sheet in the wrong inbox can lead straight to payment fraud.
A spreadsheet of customer details can end up forwarded around without anyone noticing.
ID documents can sit in “anyone with the link” folders for years.

If something goes wrong, you’re the one explaining it to the client, the insurer, and possibly regulators. Posts like The True Cost of a Breach for SMBs (and How to Avoid One) show how quickly a “small” mistake becomes expensive.

You don’t need new tools to fix this. You just need a simple way to:

Classify what you’re sending
Pick the right channel
Configure sharing sensibly
Give staff a short checklist before they hit send

Step 1: Know what you’re actually sending

Before you think about tools, decide how risky the file is if it goes to the wrong place.

Use this four-level scale:

Low-risk
- Public or semi-public material: marketing PDFs, brochures, generic templates.
- No client names, no staff data, nothing confidential.
Normal client work
- Project docs, drafts, and reports that mention client names and ordinary business info.
- Embarrassing if leaked, but not catastrophic.
Personal data (GDPR territory)
- Anything that can identify a person: names plus email, addresses, invoices with identifying details, HR files, customer lists.
- Regulators expect you to apply appropriate security here, not treat it like a flyer.
Highly sensitive
- Financial data that could enable fraud (bank details, payroll), large datasets of personal information, or special-category data (health, etc.).
- If you’d lose sleep over it leaking, it sits here.

Once you know the level, you can stop treating everything like a casual attachment.

Step 2: Choose the right channel for the job

Pick the channel based on risk, not convenience.

Low-risk and normal client work

For low and normal levels:

Use your main business cloud (Microsoft 365, Google Workspace, etc.).
Share a link instead of attaching the file.
Prefer view-only access unless editing is genuinely needed.

This reduces inbox clutter and means you can revoke access later. It also lines up with the habits you already use for sharing docs inside the team.

Personal data (most client files)

For personal data:

Still use your business cloud platform.
Share to specific people, not “anyone with the link”.
Require sign-in where possible.
Set an expiry on links.

If the file contains payment information or bank details, combine these sharing rules with the callback process in Stop Payment Fraud: A Simple Callback Playbook for Invoice & Bank-Detail Changes.

Highly sensitive information

For highly sensitive content (payroll, ID documents, large exports of customer data):

Use a secure portal or managed file-transfer solution if you have one.
If you must use email, send an encrypted or password-protected file and share the password by phone or SMS, not in the same email.

Regulators like the ICO explicitly recommend using encryption for emails containing sensitive personal data, and treating encryption as a standard control rather than a special case. See the ICO’s guidance on encryption and data transfer for examples and expectations.

Most risk comes from lazy defaults rather than bad platforms. Fix the defaults once and the day-to-day risk drops sharply.

Lock down “who can access” by default

Set your organisation’s default sharing policy to:

Internal: “Only people in your organisation”
External: “Specific people” (named email addresses)

Avoid “anyone with the link” for anything containing client or staff data. That setting is effectively “public if someone forwards it”.

When you hand off folders to a client, remember that access is a form of “user permission”. The same logic from Quarterly Access Reviews in 20 Minutes: A Small-Team Playbook applies here: keep it tight, review it occasionally, and remove access when it’s no longer needed.

Prefer least privilege every time

For each share, ask:

Do they need edit, or is view-only fine?
Can I share just one folder instead of the whole drive?
Can I remove access when the project is finished?

This is simple permission hygiene. You’re making it harder for a compromised account or misdirected email to cause maximum damage.

Use link expiry for external shares

Where your platform supports it:

Set a default expiry for external shares (e.g. 30 days).
Shorten it (e.g. 7 days) for especially sensitive content.

This keeps old links from hanging around forever in inboxes and chats.

Step 4: Safer email attachments when you can’t use links

Clients sometimes insist on attachments or can’t access cloud links. In that case, don’t just give up and send everything naked.

Encrypt or password-protect attachments

For any file containing personal or sensitive data:

Use built-in encryption/password features in Office or PDF tools.
Choose a strong, unique password for that file.
Share the password on a different channel (phone/SMS) once you know they have the email.

The ICO’s encryption guidance uses exactly this pattern as a practical example: encrypted attachment by email, password communicated separately. It’s not perfect, but it’s vastly better than sending unprotected spreadsheets around.

Slow down misdirected emails

Wrong recipients and bad CC/BCC usage are still some of the most common causes of reportable email incidents.

Basic controls that actually help:

Turn on a short send delay (e.g. 30 seconds) for outbound mail.
Make it policy to double-check the entire recipient address when sending attachments with personal data.
For bulk sends, use proper mailing tools or BCC, not long CC chains.

If someone still clicks on a malicious attachment or link, you handle the fallout with the steps in What Happens After a Phishing Click? (And What You Should Do).

You don’t need a 20-page policy. One clear page is enough if people actually follow it.

Include answers to these questions:

1. Which tools are approved?

List the only places staff are allowed to store and share client files:

Email from your business accounts
Specific cloud platforms (e.g. your Microsoft 365 or Google Workspace tenant)
Any approved secure portal or file-transfer tool

If USBs or personal cloud accounts are off-limits, say so plainly and point staff at

Safe Client File Sharing: Simple Rules for Email and Cloud Links

Why safe file sharing matters for small teams