"invoice-final.pdf" or "invoice-final-2.pdf"? Sending the wrong file is easy when names look alike. Here is how to check what you attached before the email goes out.
What Gmail does in compose (no extension)
With Attachment Preview off, clicking an attachment chip in compose, reply or Forward makes Gmail download the file. There is no native preview in compose. That is the gap this guide fills.
Option 1: Check the file before you attach it
Open the file on your computer first, then attach it from the same folder. Reliable, but slow, and it does not help when you forward an email that already has attachments.
Option 2: Preview it inside the compose window
Attachment Preview is a free Chrome extension that adds a Preview button to attachments in Gmail's compose window, so you can check the file without downloading it.
- Install Attachment Preview from the Chrome Web Store.
- In Gmail, start a new message, reply or forward, and attach your file.
- Under a PDF or image attachment, click Preview. It opens in a viewer on top of Gmail.
- Scroll through it, then press Esc to return to your draft. Your draft stays exactly as it was.
- For other file types, click Open in new tab. Files Chrome can display (such as text files) open in a tab. Files it cannot display (such as Word or Excel files) will download from that tab.
What you can check this way
| Attachment | Preview in compose |
|---|---|
| Yes, every page, in the built-in viewer | |
| PNG, JPG, GIF, WebP | Yes, in the same viewer |
| Text and other types Chrome can show | Opens in a new tab |
| Word, Excel, PowerPoint, ZIP | Downloads from the new tab; open the file on your computer to check it |
Is it private?
Yes. The extension shows the file in your browser and sends nothing anywhere. No account, no tracking. See the privacy policy.
Tips to avoid sending the wrong file
- Rename files before attaching ("Q3-report-for-Dana.pdf" beats "report (3).pdf").
- When forwarding, check every attachment that came with the original email, not just the one you added.
- Turn on Gmail's Undo Send (Settings > See all settings > General > Undo Send) and set the cancellation period to 30 seconds.
Related: Open a PDF in Gmail without downloading · How to preview an attachment in Gmail