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To change what happens when you select an email attachment, first identify your mail app, device, and file type. Previewing a file inside email, downloading it, opening the saved copy in another app, and changing the default email app are separate actions—and the available controls depend on the client and its version.
First choose the outcome you want
“Change what opens email attachments” can mean several different things. Use the attachment menu in your mail app if you want to preview, download, or save a file. If you have already downloaded it and it opens in an unexpected program, look for the operating system’s instructions for changing the default app for that specific file type. The steps vary by operating system, so there is no single procedure that applies to every computer and phone.
| What you want | What to look for | When it helps |
|---|---|---|
| Preview | Select the attachment or choose a preview action in the mail app. | Inspect a supported file without first saving a copy. |
| Download or save | Choose Download, Save, or a cloud-storage option in the attachment menu. | Keep a copy, or open it separately from the email. |
| Open or edit in another app | Download the file, then open it in a suitable installed app; supported files may offer an edit option in the mail app. | Use a preferred viewer or edit a file. |
| Change the default email app | Change the system’s default email app setting. | Choose which app handles email actions—not which app opens PDFs, images, or other attachments. |
Gmail on a computer: download or save an attachment
In Gmail on a computer, open the message and use the controls on the attachment to download it or, when available, save it to Google Drive. Google notes that some attachments cannot be added to Drive. The browser’s settings determine where a downloaded file is stored. See Google’s Gmail attachment instructions.
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If the message is in confidential mode, copying or downloading the message text and attachments may be restricted. For a video attached directly to a message, Gmail may show an error instead of a usable preview; Google’s recommended workaround is to download the video and play it with the device’s video player.
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If a Gmail attachment will not download or preview
- Check whether the file or message is subject to a restriction, including Gmail confidential mode, or whether the file type is unsupported.
- For browser-related problems, Google advises checking browser support, disabling extensions one at a time, and clearing the browser cache and cookies.
- Do not download a suspicious attachment just to test whether a setting works.
Outlook: behavior depends on the version
Outlook’s attachment behavior differs across classic Outlook for Windows, new Outlook, Outlook on the web, Outlook.com, and mobile. Account and product experience can also affect the available actions. In Outlook on the web or Outlook.com, an attachment may appear in the reading pane. Selecting it may show a preview or open it in an app associated with that file type; its menu may also offer download or a OneDrive save option. Supported Office files may be editable in a browser or desktop Office app. Unsupported file types need to be downloaded and opened with a suitable app. Consult Microsoft’s Outlook attachment instructions for the applicable experience.
Turn off attachment previewers in classic Outlook for Windows
This control is specific to classic Outlook for Windows; do not apply the path to new Outlook, Outlook on the web, or mobile.
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- In classic Outlook, go to File > Options > Trust Center.
- Select Trust Center Settings, then Attachment Handling.
- Turn off all attachment previewers, or clear the checkbox for the particular previewer you want to disable.
Microsoft says that “active content embedded in attachments (including scripts, macros, and ActiveX controls) is disabled during a preview.” It also advises previewing or opening attachments only from trustworthy sources. Disabling previewers changes preview behavior; it does not mean that every attachment is safe to open in another app.
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Apple Mail on iPhone: tap to open the attachment
Apple’s Mail guide for iPhone instructs you to open the message and tap its attachment to open the document. The guide does not establish a universal setting in Mail for choosing a different app for every attachment type. See Apple’s instructions for email attachments in Mail on iPhone.
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Changing the default email app is not changing the attachment viewer
On iPhone, Apple documents the default email-app setting at Settings > Apps > Default Apps > Email. The option is available when the desired app supports the feature. It selects which app handles email actions; it does not, by itself, select the app that opens PDF, image, or other attachment files. Apple’s instructions are at Change the default apps on iPhone.
Google also documents setting Gmail as the default mail app on iPhone or iPad, with iOS or iPadOS 18.0 or later specified for its flow. Requirements and menu labels can change; see Google’s default browser and mail app instructions.
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If a downloaded file opens in the wrong app
- Confirm which mail app and version you are using, along with your device and operating system.
- Identify the file type and decide whether you want to inspect it, save a copy, or edit it.
- Use the attachment menu to preview, download, or save the file where those options are offered.
- If the downloaded file opens in an unexpected app, follow current operating-system instructions for changing the default app for that exact file type. The steps differ across Windows, macOS, iOS, and Android.
- If Gmail preview or download fails, check for confidential-mode or unsupported-file restrictions, then try Google’s browser troubleshooting suggestions.
- If a file or sender seems suspicious, do not open it to test a setting; follow your organization’s security policy and the mail service’s warnings.
Handle unexpected attachments cautiously
Gmail warns that attachments containing unverified scripts may be unsafe and that it may not be able to scan encrypted attachments. If an email looks suspicious, Google advises against replying or downloading its attachment. This is a precaution for suspicious messages, not a claim that all attachments are dangerous. Outlook’s preview protections do not make an untrusted file safe to open, either.
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