Have you ever tried to open an email attachment and received a message like “cannot open file“? This can be extremely frustrating, especially if you need to access the information in the attachment. In this article, we will discuss why some email attachments can’t be opened, and how to fix them.
Here’s a list of the most common reasons for not being able to open an email attachment:
- The file type is unrecognized or not supported by your software or operating system
- The file is corrupted
- The file association is broken
- The attachment exceeds the size limit for your email account
- The file is blocked by your email server
- Your antivirus software has flagged the attachment as malicious
- The file is compressed into an archive format
- You have conflicting or missing email program add-ons (Outlook)
We’ll discuss each of these, along with things you can do to resolve the issue.
The file type is unrecognized or not supported by your operating system
If you try to open an email attachment and get a message like “unknown/unsupported file type,” you may need to do a little research. If the sender did not indicate what type of file it is in their message, you can ask them or use an online tool like the Toolsley File Identifier to attempt a determination on the file type. If the file has an extension on its name (i.e., MS Word documents will have the extension “.doc” or “.docx”), you can use Google to search “file extension .xxx,” inserting the extension of the file in question. If it’s a known file type, Google will return some information.
If you don’t have a program installed on your computer that can open the file type, you may be able to download a free program that will allow you to open the file. There are many free reader programs, but few of them will let you do more than view and print the file contents. Alternatively, you can ask the sender to resend the file to you in a format that you know you can open. For example, if you don’t own a copy of MS Word, you can ask them to save the file in rich text format (.rtf), a standard format for exchanging written documents, and resend it. You can also try converting the file yourself, using a site like Online-convert.com.
The file is corrupted
If you receive an error message that says the attachment is corrupt, there are a few things you can try. To start, save a copy of the attachment to your computer and then try opening it by double-clicking the file. If that does not work, open the attachment in a different program than the one you usually use (for example, if you’re trying to open a .docx file in MS Word, try opening it in WordPad or Microsoft Word Viewer).
If you still can’t open the file, it may be damaged. In that case, you can ask the sender to send you a fresh copy, or you can attempt to repair the corrupted file. Operating systems like Windows and macOS typically have tools for fixing system files, but not user data files. Many software applications include utilities for recovering damaged files, so you can try that approach if you own the corresponding software. Failing that, you’ll need a third-party utility for fixing damaged files. You can also try an online repair tool like Online.filerepair.
The file association is broken
If your computer does not have the correct program associations set up, you may get a message like “cannot open file” when trying to open an email attachment. This happens when the operating system doesn’t know which program opens a specific file type. In this case, you need to set the correct program associations for that file type.
How you go about doing this depends on your operating system and version. In some cases, you’ll be prompted to select a program from a list when you try to open the attachment. Microsoft has a support article with instructions for manually setting/changing the file association for an email attachment. If you’re using macOS, Apple has a support document explaining how to choose the app to open a file manually.
The attachment exceeds the size limit for your email account
If this happens, you won’t receive the attachment, but you’ll probably see a message appended to the email stating that the attachment was removed because it’s too large. This means your email account has a size limit for attached files, and the email service provider usually sets this limit. Ask the sender to break the attachment into smaller parts and send it that way, or if that’s not possible, they can try to reduce the size of the attachments by compressing them using a program like WinZip or StuffIt Expander. They could also upload the file to cloud storage and send you a link that allows you to download it.
The file is blocked by your email server
If you receive a message that says the attachment is blocked, your email server likely has security measures in place that are preventing the file from being downloaded. This can happen if your email account is through an organization like a school or company, and they have policies to prevent certain types of files from being downloaded. In this case, you’ll need to contact your email service provider and have them unblock the attachment, or the sender can provide it by some other means, such as uploading it to cloud storage and sending you a link that allows you to download it.
Your antivirus software has flagged the attachment as malicious
You should exercise caution if you’re trying to open an email attachment and your antivirus software pops up a message saying it’s dangerous or is being blocked for security. Do not attempt to bypass the security warning and open the attachment. You should assume that the attachment is dangerous for now.
If you know and trust the person who sent it, you can check with them about the file’s contents – but don’t reply to the email, call them instead. Email accounts get hacked and used to spread viruses and phishing messages, so don’t trust the response you might get from a reply.
If you’re not sure whether or not to trust the sender or the file, you can try scanning the attachment with a different antivirus program. If that program says the attachment is safe, you can add the sender to your trusted contacts list and then open the attachment. Otherwise, you should assume the attachment is dangerous and delete it.
The file is compressed into an archive format
If the email attachment is a .zip file or another type of archive, the sender has compressed multiple files into one file. You’ll need to decompress or unzip the file first to open it.
Most operating systems have built-in support for zip files and other standard archive formats – double-click the file to decompress it. If your system doesn’t have built-in support, you can use a free program like 7zip for Windows or Stuffit Expander for macOS.
You have conflicting or missing program add-ons in Outlook
Are you trying to open an email attachment in Outlook and getting an error message that it can’t complete the task? The problem can be caused by having multiple versions of Outlook installed on your computer, but it can also be caused by missing or conflicting add-ons for Outlook.
Begin by uninstalling all but one version of Outlook from your computer. If you’re not sure how to do this, Microsoft has a support article that explains how to uninstall Outlook, and you can also use the Office Removal Tool if needed.
If removing alternate versions of Outlook does not fix the issue, you might want to check what add-ons you are currently using. Removing unneeded add-ons and temporarily disabling others may resolve the issue. Microsoft has a support article on working with Office add-ons here.
There are a few other reasons why an email attachment might not be able to be opened, but these are the most common ones. With a bit of troubleshooting, you should be able to fix the problem and open the attachment. If you’re still having trouble, you can always contact your email service provider for help. Thanks for reading!