How To Send A Large Attachment In Outlook – File Size Compression Methods

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File size limits in Outlook can stop your delivery cold. Sending large attachments requires a specific workaround to avoid bounce-backs. Understanding How To Send A Large Attachment In Outlook is essential for anyone who regularly shares high-resolution images, video files, or large presentations. This guide walks you through every reliable method, from built-in tools to third-party services.

Outlook’s default attachment limit is 20 MB for most accounts. If your file exceeds that, you get an error message. But you have options. Let’s look at the best ways to get your file through.

Why Outlook Rejects Large Attachments

Outlook enforces size limits to protect email servers and recipients. When you attach a file larger than 20 MB, the system blocks it. This is a server-side restriction, not just a warning. You cannot bypass it by compressing the file slightly.

Some organizations set even lower limits. Check with your IT department if you are unsure. The limit applies to the total size of all attachments combined, not just one file.

How To Send A Large Attachment In Outlook

This is the core method. Outlook offers a built-in feature called “Share” or “Attach as Copy” depending on your version. The key is to use OneDrive or SharePoint integration.

Method 1: Using OneDrive Integration

This is the simplest method for most users. It works with Outlook 2016, 2019, and Microsoft 365.

  1. Open a new email message in Outlook.
  2. Click the “Attach File” button in the ribbon (paperclip icon).
  3. Select “Browse This PC” to find your file.
  4. If the file is larger than the limit, Outlook will prompt you to upload it to OneDrive instead.
  5. Choose “Upload to OneDrive and share a link.”
  6. Outlook uploads the file to your OneDrive and inserts a download link in the email body.
  7. You can set permissions: “Recipients can edit” or “Recipients can view only.”
  8. Send the email as usual.

This method bypasses the attachment size limit entirely. The recipient clicks the link to download the file from OneDrive. They do not need a Microsoft account to access it, though they may need to verify their identity.

Method 2: Using SharePoint Integration

If your organization uses SharePoint, you can upload files there and share links. This is ideal for team collaboration.

  1. Upload your file to a SharePoint document library.
  2. In Outlook, compose a new email.
  3. Click “Attach File” and select “Browse Web Locations.”
  4. Choose “SharePoint” and navigate to your file.
  5. Select the file and click “Insert as Link.”
  6. Outlook inserts a link to the SharePoint file.
  7. Set permissions as needed and send.

This method keeps the file in a centralized location. Multiple people can access it without emailing copies. It also preserves version history.

Method 3: Using Outlook Web App (OWA)

If you use Outlook in a browser, the process is similar. OWA automatically offers to upload large files to OneDrive.

  1. Log in to Outlook on the web.
  2. Click “New message.”
  3. Click the paperclip icon to attach a file.
  4. Select the file from your computer.
  5. If the file is too large, OWA shows a message: “This file is too large. Upload to OneDrive?”
  6. Click “Upload to OneDrive.”
  7. The file uploads and a link appears in the email.
  8. Adjust permissions if needed and send.

OWA also supports drag-and-drop for attachments. Just drag the file into the email window. The same upload prompt appears.

Compressing Files Before Attaching

Sometimes you want to keep the file as an actual attachment, not a link. Compression can help, but only if the file is slightly over the limit. For example, a 25 MB file might compress to 18 MB.

Using Built-In Compression Tools

Windows and Mac both have built-in compression. On Windows, right-click the file and select “Send to” then “Compressed (zipped) folder.” On Mac, right-click and choose “Compress.”

This works best for text files, spreadsheets, and presentations. Images and videos compress less effectively. A 50 MB video might only shrink to 45 MB.

Using Third-Party Compression Software

Tools like 7-Zip, WinRAR, or WinZip offer better compression ratios. They also let you split files into smaller parts. For example, you can split a 100 MB file into five 20 MB chunks. Send each chunk in separate emails.

This method is cumbersome for the recipient. They must download all parts and recombine them. Use it only as a last resort.

Using Cloud Storage Services

If you do not have OneDrive or SharePoint, other cloud services work. Google Drive, Dropbox, and Box all allow file sharing via links.

Google Drive Method

  1. Upload your file to Google Drive.
  2. Right-click the file and select “Share.”
  3. Set permissions to “Anyone with the link can view.”
  4. Copy the link.
  5. In Outlook, paste the link into the email body.
  6. Optionally, add a note explaining the link.

This method is free for files up to 15 GB. Larger files require Google One storage. The recipient clicks the link to download.

Dropbox Method

  1. Upload your file to Dropbox.
  2. Click the “Share” button next to the file.
  3. Select “Create a link.”
  4. Copy the link.
  5. Paste it into your Outlook email.

Dropbox offers 2 GB of free storage. Paid plans allow larger files. The link works for anyone, even without a Dropbox account.

Box Method

  1. Upload to Box.
  2. Click the “Share” icon.
  3. Select “Get shared link.”
  4. Copy the link.
  5. Paste into Outlook.

Box provides 10 GB of free storage. It is popular in business environments.

Using Email Services That Support Large Attachments

Some email providers offer higher attachment limits. For example, Gmail allows 25 MB, but files over 25 MB are automatically uploaded to Google Drive. Outlook.com (free) has a 34 MB limit, but files over 10 MB may be uploaded to OneDrive.

If you use a custom domain with Microsoft 365, the limit is 20 MB. But you can send links to files stored in OneDrive or SharePoint.

Using Third-Party File Transfer Services

Services like WeTransfer, SendAnywhere, and Filemail specialize in sending large files. They work independently of your email provider.

WeTransfer

  1. Go to wetransfer.com.
  2. Enter the recipient’s email address and your email.
  3. Add a message.
  4. Upload your file (up to 2 GB free).
  5. Click “Transfer.”
  6. WeTransfer sends an email to the recipient with a download link.

This method does not use Outlook at all. You send the file through WeTransfer’s system. The recipient gets an email from WeTransfer, not from you directly. You can also copy a link and paste it into your own Outlook email.

SendAnywhere

  1. Go to send-anywhere.com.
  2. Upload your file (up to 10 GB free).
  3. Enter the recipient’s email or generate a 6-digit key.
  4. The recipient enters the key to download.

This method is secure and does not require an account. The file is encrypted during transfer.

Filemail

  1. Go to filemail.com.
  2. Upload your file (up to 5 GB free).
  3. Enter recipient email and your email.
  4. Send.

Filemail offers tracking and notifications. You can see when the recipient downloads the file.

Setting Up OneDrive For Automatic Uploads

If you frequently send large files, configure Outlook to always upload to OneDrive. This saves time.

  1. Open Outlook.
  2. Go to File > Options > Mail.
  3. Under “Send messages,” find “When attaching files larger than the following size, upload to OneDrive.”
  4. Set a threshold, such as 10 MB.
  5. Click OK.

Now, any attachment over 10 MB automatically uploads to OneDrive. Outlook inserts a link instead of the file. You can still override this by choosing “Attach as Copy” manually.

Common Issues And Solutions

Recipient Cannot Access The Link

If the recipient cannot open the OneDrive link, check permissions. Set the link to “Anyone with the link can view” if it is a public file. For sensitive files, use “Specific people” and add their email addresses.

Sometimes corporate firewalls block OneDrive links. In that case, use a different method like WeTransfer or Google Drive.

File Is Too Large For OneDrive

OneDrive free tier allows files up to 250 MB. Paid plans allow up to 100 GB per file. If your file exceeds that, use a dedicated file transfer service.

Outlook Crashes When Attaching Large Files

This can happen if your computer runs low on memory. Close other programs before attaching. Alternatively, upload the file to cloud storage first, then share the link.

Best Practices For Sending Large Attachments

  • Always compress files before uploading. Even a small reduction helps.
  • Use descriptive file names so recipients know what they are downloading.
  • Include a brief message in the email explaining what the file contains.
  • Set expiration dates on shared links if the file is time-sensitive.
  • Use password protection for sensitive files. Most cloud services offer this.
  • Avoid sending executable files (.exe, .bat) as they may be blocked.

Frequently Asked Questions

What Is The Maximum Attachment Size In Outlook?

Outlook’s default limit is 20 MB for Microsoft 365 and Exchange accounts. Free Outlook.com accounts allow up to 34 MB. However, files over 10 MB are often uploaded to OneDrive automatically.

Can I Send A 100 MB File Via Outlook?

Yes, but not as a direct attachment. You must use OneDrive, SharePoint, or a third-party service. Upload the file to cloud storage and share a link in your email.

How Do I Send A Large Video File In Outlook?

Upload the video to OneDrive, Google Drive, or YouTube (unlisted). Then paste the link into your Outlook email. This avoids size limits and preserves video quality.

Why Does Outlook Say “File Too Large” Even After Compression?

Compression may not reduce the file enough. Some file types, like already compressed images or videos, shrink very little. Use cloud storage or a file transfer service instead.

Is It Safe To Send Large Attachments Via OneDrive Links?

Yes, if you set proper permissions. Use “Specific people” for sensitive files. Enable expiration dates and password protection for extra security.

Conclusion

Sending large attachments in Outlook does not have to be frustrating. The built-in OneDrive integration is the easiest solution for most users. For files over 250 MB, use a dedicated service like WeTransfer. Always compress files when possible and set appropriate permissions. With these methods, you can send any file size without bounce-backs. Try the OneDrive method first—it is fast, secure, and integrated into Outlook. Your recipients will appreciate the simplicity.