What is Outlook Attachment Size and How to Increase the Size Limit

Created On:
May 2, 2024
Updated On:
May 2, 2024
What is Outlook Attachment Size and How to Increase the Size Limit

Sending large files through Microsoft Outlook can be challenging due to attachment size limits. This article provides simple solutions, including using cloud services and modifying system settings, to bypass these restrictions. 

Whether you're new to Outlook or an experienced user, these tips will help you send large files efficiently and effectively.

Outlook Attachment Size Limit  

Outlook restricts the size of email attachments you can send. If your attachments exceed this limit, you won't be able to send your email. Instead, Outlook suggests placing the file in a shared location and sending a link to it. 

For users of Outlook 2013 and later, the maximum attachment size is 20 megabytes(20 MB). If the attachments are larger than this, you'll need to find another way to send them.

For those using a Microsoft Exchange Server Account, the limit is even lower, at just 10 megabytes. These limits are set by your server's Transport Settings Properties, not by Outlook itself.

If you're considering bypassing these restrictions by modifying your computer's registry settings, make sure to back up your registry first. This precaution helps protect your data in case anything goes wrong during the modification process.

How to Increase Outlook Attachment Size Limit

Outlook limits email attachment sizes to 20MB, which can be restrictive for sending larger files. Although it's not recommended to modify these settings yourself, you can increase the limit by editing your computer's registry.

If you choose to adjust the Outlook attachment size limit on a Windows system, here’s a step-by-step guide:

Step 1: Press `Windows + R` to open the Run dialog box.

Step 2: Type `regedit` and click OK to open the Registry Editor.

Step 3: Navigate to the registry entry for your version of Outlook: 

  • For Outlook 2019 and 2016: `HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences`
  •    - For Outlook 2013: `HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Preferences`
  •    - For Outlook 2010: `HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences`

Step 4: Look for the `MaximumAttachmentSize` value. If it’s not there, you can create it by right-clicking in the window, selecting Edit → New → DWORD Value, and naming it `MaximumAttachmentSize`.

Step 5: Double-click on `MaximumAttachmentSize` and enter the new limit (in kilobytes) in the Value Data box, then click OK.

Step 6: Close the registry editor and restart Outlook to apply the changes.

Remember, altering the registry can be risky, so consider this option carefully. If you’re not comfortable with these steps, it might be safer to use cloud services to share larger files instead. 

Also, there is currently no way to change the Outlook attachment size limit on your mobile (android/iOS). You will have to do this via the web or on your computer Outlook app.

If you are struggling to set up your Outlook account, read the Complete Guide to Configuring Outlook SMTP Settings

Sending Large Files Through Outlook: Tips to Remember

Sending large files through Outlook can sometimes be a challenge due to attachment size limits. However, there are several easy methods you can use to bypass these limitations without altering your computer’s settings.

1. Compress Your Files: You can reduce the size of your files by compressing them. Simply right-click the file and select 'Compress.' Additionally, consider installing an add-in for Outlook, which can automatically compress files to help fit them within your email's size limits.

2. Split the File: If compressing isn’t enough, you can split a large file into smaller parts using tools like 7-Zip. This tool can segment your file into manageable pieces, such as 7MB chunks. However, be cautious, as splitting files can sometimes modify them.

3. Use Cloud Storage Services: One of the most reliable ways to send large files is via cloud storage services such as OneDrive, Dropbox, iCloud, or Google Drive. Here’s how you can do it:

  • Upload your file to the cloud service of your choice.
  • Once uploaded, copy the link to the file.
  • Paste this link into your email. The recipient can then access and download the file through the link.

4. Share via SharePoint: If your workplace uses SharePoint, you can upload your file there and share a link just as you would with other cloud services.

5. Resize Large Images: Outlook offers a feature to resize large images when sending them automatically. When attaching the images, go to File → Info, select 'Images Attachments,' and choose 'Resize large images when I send this message.'

These methods allow you to efficiently manage large files in Outlook without requiring technical modifications or risking alteration. 

Read How to Schedule Emails in Outlook here


In conclusion, while Outlook imposes limits on the size of email attachments, there are several effective strategies for sending large files. Whether you choose to adjust your registry settings, compress files, use cloud storage, or employ other tools, it's important to select the method that best fits your needs and comfort level. 

Always remember to prioritize data safety, especially when making changes to system settings. 

By exploring these alternatives, you can continue to communicate effectively and efficiently, regardless of file size limitations.

What’s a Rich Text element?

The rich text element allows you to create and format headings, paragraphs, blockquotes, images, and video all in one place instead of having to add and format them individually. Just double-click and easily create content.

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Static and dynamic content editing

A rich text element can be used with static or dynamic content. For static content, just drop it into any page and begin editing. For dynamic content, add a rich text field to any collection and then connect a rich text element to that field in the settings panel. Voila!

How to customize formatting for each rich text

Headings, paragraphs, blockquotes, figures, images, and figure captions can all be styled after a class is added to the rich text element using the "When inside of" nested selector system.

Author’s Details

Sattwik Das

Sattwik is a Digital Marketing professional at Smartlead. He is a dedicated content writer who focuses on juggling words to bring out meaningful content. He is experienced in well-researched and SEO-optimized content creation, content editing, and copywriting for various businesses throughout the globe. His expertise in SEO, SMM, and SMO with a touch of creativity helps businesses grow and maximize their credibility and sales.


Edited by:

Sattwik Das


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