Use “Open In Browser” For Unknown Files Before Downloading

Many email and cloud platforms allow you to preview files in your browser, so opening unknown documents this way first is a simple way to reduce the risk of running harmful content on your device.

Why This Matters

Unexpected attachments are one of the most common ways malware and phishing attacks reach businesses.

Opening a file directly in a desktop application can allow embedded content, such as macros or scripts, to run if enabled.

Previewing a file in your browser, where supported, limits this behaviour and gives you a chance to assess the content before downloading it.

How To Preview Files In Microsoft 365

In Outlook on the web or OneDrive:

1. Click on the attachment or file.
2. Select ‘Preview’ or ‘Open in browser’.
3. Review the content without downloading it.

Office files such as Word, Excel and PDFs will typically open in a web-based viewer.

How To Preview Files In Google Workspace

In Gmail or Google Drive:

1. Click the attachment or file.
2. Select ‘Preview’ (often shown as an eye icon).
3. Review the file in the browser window.

You can then decide whether it is safe to download or open fully.

What To Watch For

Even when previewing files, be cautious of:

• Requests to enable editing or macros after download.
• Links inside documents that prompt further action.
• Files from unknown or unexpected senders.

If in doubt, verify with the sender before opening fully.

A Practical Approach

Use browser preview as a quick first step when dealing with unexpected files.

It only takes a moment and adds an extra layer of caution before opening content directly on your device, helping reduce the risk of accidental malware execution.