Symptoms
- Clicking the attachment does nothing
- Error saying the file type isn't supported
- Attachment appears but downloads as 0 bytes
- 'This file may be dangerous' warning blocking download
Likely causes
- CommonEmail provider blocks certain risky file typesProviders commonly block executable files and some compressed archives for safety.
- CommonNo app installed that can open the file typeSpecialized file formats need matching software to view.
- PossibleAttachment didn't fully download or upload correctlyLarge attachments can fail silently over a poor connection.
- Less commonAttachment renamed or corrupted in transitSome email systems alter file names or formats unexpectedly.
What to do
- Check what type of file it is from the file name extension.
- If it's a common type like PDF or image, try opening it in a web browser rather than downloading first.
- Ask the sender to resend it, possibly renamed or in a different format, if it's blocked or won't open.
- Try accessing the email from a different device or the webmail site instead of an app.
- Install the specific app needed to open specialized file types (like CAD or design files).
- Check your email's spam or blocked-content settings for restrictions on certain attachment types.
When to call a pro
If you receive a suspicious attachment from what looks like a trusted contact, verify with them directly before opening it.
Safety
Use caution
Never open an attachment from an unknown or unexpected sender, even if it appears to open fine, since it can carry malware.