What is .OTM File Extension?

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We all know that .exe files can be dangerous. However, they’re not the only file types that we need to be wary about. There are other potentially dangerous file extensions out there, many of which you wouldn’t expect.

So, why should you want to know if files on your system are dangerous? Well, obviously, these files can cause irreversible damage to your PC. For example, once clicked, they can trigger codes that will send information about your device to hackers. You wouldn’t want that to happen, right?

In this article, we look into one odd file extension that many of you have encountered already. Hopefully, after reading, you will know whether or not it’s dangerous or safe. We’re talking about the .OTM file extension.

About the .OTM File Extension

The .OTM file extension is a file type associated with the software program Micro Cookbook. While it sounds legit, the only problem is that it is no longer supported today. It was developed long ago for Microsoft Windows 3.x.

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This file stores macros written for MS Outlook. It could also hold scripted apps developed in Visual Basic Editor.

Now, can .OTM file contain viruses? The answer is yes. Again, as with other file types, many cybercriminals nowadays disguise malicious entities as legit files. So, at first glance, you might be convinced that there is nothing wrong with the .OTM file on your PC. Unless you run a quick scan, it is then when you get notified that it could be malicious.

However, you need not worry a lot because as long as you have an active and up-to-date anti-malware software, then you should be safe and protected.

How to Open a .OTM File?

Though it seems like an unsupported file type, there are still many programs that can open .OTM files. If you don’t have a compatible software, you will see the Windows error message “How do you want to open this file” or “Windows cannot open this file.” But if you are only having a hard time opening the file correctly, simply long-press the file or right-click on it. After that, click Open with and select a compatible application.

Alternatively, you can use any of the following programs to open or convert OTM files:

Micro Cookbook

Micro Cookbook is a Windows-based software. It is designed for those who love to cook.


Origin is a proprietary computer application designed for data analysis and interactive scientific graphing. Developed by OriginLab Corporation, it has since inspired a number of platform-independent open-source programs.

Microsoft Outlook

Any code created in the Microsoft Outlook VBA module is stored in a file that is named VBAProject.OTM. Should you want to move the project to another device, you have to copy the entire .OTM file, but don’t expect the macros to run completely until that device has used any Macro commands. In addition, if the macro security is set to high, which is the default setting, any unsigned projects will not run.

How to Resolve Issues with OTM Files

If you encounter any problems with OTM files, here are some steps you can take:

  1. Make sure the OTM file is associated with the correct application. To do this, right-click on the OTM file and select Open with, and then Choose another app. Next, choose another program and be sure that the Always use this open to open .otm files is ticked.
  2. Keep your software updated. An outdated software application might not actually open the file. Only the current version of Micro Cookbook supports the latest OTM file format. To update your software, visit the manufacturer’s website and check for any updates.
  3. Check if your OTM file is not infected by viruses or malware entities. Use a reliable antivirus program to scan the file.


.OTM files are legit files that are supported by programs like Micro Cookbook, Outlook, and Origin. Should you have any problems with it, you can resolve them by following the tips we have in this article.

What other file types do you think are suspicious? Let us know in the comments!

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