When receiving an email, sometimes we come across attachments that we are unfamiliar with, such as the MIME or SMIME formats. It may be the first time you see it on your email, so ideally, you have to understand it first before trying to open it.
MIME means Multipurpose Internet Mail Extensions. For SMIME, the S stands for Secure. It is a type of format that allows you to receive or even send non-text email attachments. For instance, the file contains an audio or video file and not a text document. MIME email formats also support characters in files beyond the ASCII.
These email attachment files also act as encryption to your emails. It helps protect your emails from phishing attacks and enables you to sign your emails digitally. If you don’t know how to open your email with the MIME attachment, continue reading below to get an idea of how to do it.

How to Open MIME or SMIME Email Attachments on your Computer
There are several ways on how you can open MIME or SMIME email attachments on a Mac computer or Windows 10 PC. Check out each method below.
Method #1 – Use Outlook to Open MIME or SMIME Files

You can use Microsoft Outlook email client to download the MIME email attachment and open it on a notepad app.
- Open the email message containing the MIME attachment.
- Highlight and copy all MIME texts.
- Launch your Notepad app.
- Now, paste the MIME attachment.
- Highlight and select all the text before the email header. Delete all texts.
- Select Save as. On the file name, add the .eml extension in the end.
- After saving the file, navigate to where you saved it.
- Open the file to read the MIME attachment.
Method #2 – Download a MIME Opener Software

Another way to open and extract MIME email attachments is to use the software, such as WinZip, Open Freely, and Universal Viewer. In the software, unzip the MIME archive file and save it in your local computer folder. It will extract the files for you to read the text easier.
Method #3 – Access Free MIME Text Viewer Online
Alternatively, there are available MIME text viewers that you can use online. All you have to do is open the viewer on any browser. Upload the MIME file, and it will open the file in a readable format.
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