Unable to attach files in Outlook! – [How to Fix it?]

Last Updated on June 29, 2023 by Amit Bansal

Many business professionals rely on email to deliver important communications. Unfortunately, the email system within Outlook can sometimes be a hindrance if you use some types of attachments.

While most people can use Outlook without any problems, you may experience an issue when attaching large files to an email message.

In some cases, users are unable to attach files to email in Outlook, there must be some technical glitch, or some must be in your control, there are multiple times I personally encountered the same situation, I need to send an especially important email message with an attachment very badly, but unable to send.

In this article, there are a few tricks and tips in Outlook which help to get rid of the problem.

Why Can’t I Attach Files in Outlook?

Frankly speaking below reasons really such minor modifications which the majority of users are already aware of:

  • Attachment File size, [Raise Attachment Limit].
  • Convert files containing suspicious extensions
  • Check and Compress File size before attachment.
  • Restart Microsoft Outlook
  • Update Browser

Attachment File size [Raise Attachment Limit]

Outlook’s email client sets a maximum limit of [20 MBs] for every email attachment including email content. Not even Outlook every email provider set up attachment limit size. you can face this problem everywhere. Therefore, it is better to verify the attachment size before trying to add or upload it.

You can utilize the maximum hide limit provided by Outlook and raise the attachment limit.

Convert files containing suspicious extensions

Outlook allows users to attach most extension files, sometimes it blocks a specific type of file containing malware extensions, which causes security issues for both the users (sender and receiver). Still, you are sending a valid file and Outlook reveals a concern for the file.

You can simply convert the file into (.zip file), and you can easily send the file through Outlook.

Check and Compress the File size before the attachment

Converting your file into (.zip file), not only change file extension but also compress file size to the maximum limit in case. To check the original file size, simply click the right mouse button, then Properties (the last option of the dialog box).

Check and Compress File size before attachment

The file properties dialog box reveals the size of the file which brings the issue of Can’t Attach File in Outlook, to convert the file into (.zip file), click “Add to archive“, and you will compress the zip file, which consists of your original file, and the file size also reduced to attach.

Restart Outlook

Restarting Outlook, and cleaning up every technical glitch that comes across, it was observed restarting Outlook resolves minor issues in many cases.

Update Browser

Regular updation of the browser is very crucial, it is recommended to update it to the latest version and keep your browser updated, the previous version is sometimes unable to resist glitches which cause a few uncertainties in the normal working of the application.

If you are using paid Microsoft 365, it is recommended to contact customer care.

Solutions and Fixes

Compressing Large Files

One common issue when trying to attach files in Outlook is the file size. The platform has a maximum attachment size that you need to consider.

To overcome this limitation, we recommend compressing your files into a zip file before attaching them. This will reduce the file size, making it easier to send via Outlook.

Using OneDrive for Attachment Sharing

Another solution to the file size problem is to use OneDrive, Microsoft’s cloud storage service. Instead of attaching the file directly to the email, you can share a OneDrive link with the recipient.

This method allows you to share large files without worrying about attachment size limitations.

Changing File Extensions

In some cases, Outlook may prevent certain file extensions from being attached due to security reasons.

To resolve this issue, try changing the file extension or saving the file in another format, such as a PDF or a text file. This may allow you to attach the file without encountering errors.

Updating to the Latest Outlook Version

It’s essential to keep your Outlook software up-to-date, as outdated versions may cause conflicts or compatibility issues when attaching files.

Make sure you’re using the latest version of Outlook, whether you’re on Outlook 2016, 2019, or Outlook for Microsoft 365.

Updating to the latest version ensures that you have the most recent features and security patches.

Checking Internet Connection

A reliable internet connection is crucial for attaching files in Outlook.

If you experience issues when attaching files, check your internet connection to ensure it is stable and working correctly. If necessary, reset your modem or router and try again.

Using Outlook App for Android and iPhone

If you’re facing issues with attaching files on the desktop version of Outlook, try using the Outlook app for Android or iPhone.

The mobile app may offer a smoother experience for attaching files and is designed to work seamlessly with your smartphone.

Remember to follow these suggestions only when relevant and applicable to your situation.

Additionally, ensure the information you provide is accurate and true to the best of your knowledge.

Prevention Methods

Antivirus Software

One effective strategy to prevent attachment issues in Outlook is to use reliable antivirus software.

Antivirus software helps to scan and detect possible malicious files, including malware and other security threats.

By using antivirus software, we significantly minimize the risk of attachment issues due to compromised file types or file name extensions.

Email Content and Attachment Awareness

Another crucial preventive measure is to be aware of the content of the emails we receive and the attachments included.

Before downloading or opening any attachment, ensure that it comes from a trusted source and has a familiar file type.

Additionally, it’s essential to educate ourselves about the file name extension to understand which file types correspond to which applications.

Having this knowledge helps to avoid mistakenly opening an attachment with a dangerous file type.

Regular Updates

Finally, it is vital to keep our Outlook software regularly updated. Updates may include necessary security patches, bug fixes, and performance enhancements.

Staying updated ensures that we have the latest protection against attachment issues or potential security threats.

By following these best practices, we effectively reduce the chances of encountering issues when trying to attach files in Outlook, maintaining a secure and functional email environment.

Microsoft Resources and Support

Microsoft 365 Subscription Benefits and Support

As Microsoft 365 subscribers, we benefit from a variety of tools and functionalities within Outlook. One of the significant advantages is the ability to attach files to our emails.

We can easily attach documents, pictures, and other items in our messages, making collaboration convenient and streamlined.

Additionally, with Microsoft 365, we can share our calendar events, set our sharing preferences, and access various useful features like automatic saving and seamless synchronization across devices.

However, some users may experience issues, such as being unable to attach files in Outlook.com.

If you face any such problem, remember that as Microsoft 365 subscribers, we have access to comprehensive support resources.

From troubleshooting guides to detailed articles, Microsoft provides a wealth of information to assist us in resolving any difficulties we encounter.

Training Courses and Communities

To make the most of Outlook.com and its features, Microsoft offers training courses, webinars, and other learning resources.

These instructional materials not only help us understand Outlook’s full potential but also provide tips and tricks for effective email management.

Furthermore, Microsoft’s online communities enable us to connect with other professionals, ask questions, and share our expertise.

Platforms like Microsoft Q&A and the Microsoft Community forums are invaluable sources of information for tackling specific issues, like Outlook 2013Outlook 2010, or Outlook 2007 attachment challenges.

Contacting Technical Support

When our concerns are highly technical, or we cannot find the appropriate solution through articles and communities, Microsoft’s technical support is there to assist.

To receive support in Outlook.com, click here and enter your query. If self-help doesn’t solve your problem, you can select “Still need help?” and choose “Yes.”

Remember that to contact Microsoft’s technical support on Outlook.com, we need to be signed in. If you can’t sign in, click here for further assistance.

Microsoft’s support staff is knowledgeable and well-equipped to handle attachment issues like computer viruses or problems with forwarding attachments.

In conclusion, as Microsoft 365 subscribers, we have access to numerous resources and support options to tackle common and complex challenges within Outlook.

Our proactive approach and the available support channels assure a seamless experience, making Outlook.com an invaluable tool in our daily lives.


In this article, we have covered various methods to resolve issues related to attaching files in Outlook. It is essential to keep in mind the file size limitations, as exceeding the 29 MB limit can cause problems.

Some common solutions include trying to open Outlook in safe mode and disabling add-ins, which can sometimes interfere with the attachment process.

Another essential consideration is to ensure that the file type you’re attempting to attach is not blocked by Outlook.

If you’re still experiencing issues, try forwarding the original email with the attachment instead of replying, as attachments won’t be included in reply messages.

We hope that by following these steps, attaching files in Outlook becomes a smooth and hassle-free process for you.

Frequently Asked Questions (FAQs)

Why can’t I attach files in Outlook Office 365?

There could be several reasons why you’re unable to attach files in Outlook Office 365, such as file size limitations, file format restrictions, and slow internet connections.

To troubleshoot, try attaching a smaller file, ensure the file format is supported, and check your internet connection.

Additionally, you can start Outlook in safe mode to ensure add-ins are not causing the issue.

How to resolve attachment issues in Outlook Android?

First, ensure that your Outlook app is up to date and that your device has enough storage space. Also, check your internet connection to ensure it’s stable.

If the issue persists, try restarting your device or reinstalling the Outlook app.

What causes Outlook to not attach files when replying?

This issue may arise due to a slow internet connection, large file size, or incompatibility with the attachment format.

To resolve this, you can try restarting your computer, making sure your internet connection is stable, and checking the attachment size and format limitations.

How to fix difficulties attaching files in Outlook for Mac?

To fix attachment issues in Outlook for Mac, make sure your Outlook application is up to date, and try restarting the app.

Additionally, check your file size limits and file format compatibility. If the problem persists, consider creating a new email account and testing the attachment feature on it.

How to enable attachments in Outlook email?

Ensure that the file preview feature is enabled in the Trust Center. In Outlook, select File > Options >> Trust Center >> Trust Center Settings >> Attachment Handling.

To enable a specific attachment previewer, click Attachment and Document Previewers, and check the box for the desired previewer. For more details, visit Microsoft Support.

What are common solutions for Outlook Web App attachment issues?

If you’re unable to attach files in Outlook Web App, try the following solutions: clear your browser cache, ensure that your browser is up to date, and review the file size and format restrictions.

If the issue persists, consider using a different browser or trying the attachment feature on a different device.

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Amit Bansal

Hello, my name is Amit Kumar Bansal, and I am the founder of MailSmartly.com. Through this blog, I focus on Microsoft Outlook, offering insightful and informative content. Additionally, I produce educational videos on YouTube to further enhance the understanding of my audience. visit my YouTube Channel

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