Not being able to open an attachment is usually down to one of three things: the email client is blocking the file type for security reasons, your browser or device is preventing the download, or you do not have an application that can open the file format. Here is how to work through each scenario.

Outlook Blocking Certain File Types

Outlook blocks many file types by default for security — including .exe, .bat, .vbs, and others. If you see a message like Outlook blocked access to the following potentially unsafe attachments, the file was blocked before you could even try to open it.

If you are certain the attachment is safe and came from a trusted sender, the safest approach is to ask the sender to compress it into a .zip file and resend it, or to share the file via a cloud storage link (Google Drive, OneDrive, Dropbox) instead of an attachment.

Note: Be cautious with any attachment you were not expecting, even from people you know. Attachments are a common way malware is delivered. If in doubt, ask us before opening.

Gmail Blocking Certain Attachments

Gmail similarly blocks certain file types. If Gmail prevents a download, the attachment will appear greyed out with a warning. The same advice applies — ask the sender to share via Google Drive instead.

You Do Not Have the Right App

If you can download the file but cannot open it, you may not have software that reads that format. Common examples:

  • .docx / .xlsx / .pptx — requires Microsoft Office, LibreOffice, or Google Docs
  • .pages / .numbers / .key — Apple formats; open at iCloud.com if you do not have a Mac
  • .pdf — open in any browser, or install Adobe Acrobat Reader (free)
  • .heic — iPhone photo format; Windows needs an update or the HEIF Image Extensions from the Microsoft Store

Browser Download Issues

If you are using webmail (Gmail, Outlook.com) and the download button does nothing, try:

  1. Clearing your browser cache and cookies
  2. Trying a different browser
  3. Disabling browser extensions temporarily