How To Send Large Zip Files In Outlook – Compressing Files Before Email Attachment

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Zipping a large file often fails to reduce its size enough for Outlook, so you should use a file-sharing service like OneDrive instead. Understanding how to send large zip files in outlook is essential when you need to share bulky projects or archives. Outlook has a strict 20–25 MB attachment limit, and even a compressed zip file can exceed this cap. This guide walks you through every reliable method, from built-in cloud links to third-party tools, ensuring your files reach recipients without bounce-backs or errors.

Many people assume zipping solves everything. But a zip file only shrinks certain file types, like text or spreadsheets, while images and videos barely compress. When you try to attach a 50 MB zip folder, Outlook will block it. That is why you need alternative approaches. Below, you will find step-by-step instructions, troubleshooting tips, and best practices for sending large zipped files through Outlook.

Why Zipping Alone Doesn’t Work For Outlook

Compression algorithms have limits. A zip file can reduce a Word document by 90%, but a JPEG image might only shrink by 2–5%. If your original folder is 100 MB, the zip might still be 95 MB—far above Outlook’s limit. Additionally, some email servers reject attachments over 10 MB even if Outlook allows them. This is why knowing how to send large zip files in outlook involves more than just right-clicking and compressing.

Another issue is recipient compatibility. Some corporate email systems block zip files entirely due to security risks. They may flag .zip extensions as potential malware. So even if your zip file is under the size limit, it might get quarantined. The solutions below bypass these restrictions by using cloud storage or splitting techniques.

How To Send Large Zip Files In Outlook

This section covers the most effective methods. Each approach works with Outlook 2016, 2019, 2021, and Microsoft 365. Follow the steps that match your situation.

Method 1: Use OneDrive Or SharePoint

Microsoft’s own cloud services integrate seamlessly with Outlook. When you attach a file that is too large, Outlook automatically offers to upload it to OneDrive and send a link instead. This is the simplest way to send large zip files without third-party tools.

  1. Open Outlook and compose a new email.
  2. Click the “Attach File” icon (paperclip) in the ribbon.
  3. Select your zip file from your computer.
  4. If the file exceeds Outlook’s limit, a prompt appears: “This file is too large. Upload to OneDrive?”
  5. Choose “Upload and Share as a OneDrive Link.”
  6. Outlook uploads the zip to your OneDrive and inserts a shareable link in the email body.
  7. Adjust permissions if needed (e.g., “Recipients can edit” or “View only”).
  8. Send the email.

This method works for files up to 250 GB if you have enough OneDrive storage. Recipients click the link to download the zip directly. They do not need a Microsoft account to access the file, though they may need to verify their email.

Method 2: Split The Zip File Into Smaller Parts

If you prefer direct attachments, you can split a large zip into multiple smaller archives. This method is useful when recipients have slow internet or corporate restrictions on cloud links. You will need a file splitting tool like 7-Zip or WinRAR.

  1. Install 7-Zip (free) or WinRAR (trial).
  2. Right-click your original folder and select “Add to archive.”
  3. In the compression settings, look for “Split to volumes” or “Split into parts.”
  4. Enter a size like “20M” (20 MB) or “10M” to ensure each part fits Outlook’s limit.
  5. Click OK. The tool creates multiple .zip files named like “archive.zip.001”, “archive.zip.002”, etc.
  6. Attach each part to separate emails, or combine them into a single email if the total size of all parts is under 25 MB.
  7. Send the first part with instructions to download all parts and use the same tool to extract.

Be aware that recipients must download all parts and use compatible software to rejoin them. This can be confusing for non-technical users. Also, sending multiple emails may clutter inboxes. Use this method only when cloud sharing is not an option.

Method 3: Use A Third-Party File Transfer Service

Services like WeTransfer, Dropbox, or Google Drive offer free file sharing with larger limits. WeTransfer allows up to 2 GB for free, while Google Drive gives 15 GB of storage. These services generate a download link that you paste into your Outlook email.

  1. Go to the file transfer website (e.g., wetransfer.com).
  2. Upload your zip file following the site’s instructions.
  3. Enter your email and the recipient’s email if required.
  4. After upload, copy the download link provided.
  5. In Outlook, compose a new email and paste the link into the body.
  6. Add a brief message explaining the link leads to the zip file.
  7. Send the email.

Most services set an expiration date (e.g., 7 days) for the link. Inform your recipient to download the file promptly. Some corporate networks block these sites, so verify with your IT department first.

Method 4: Compress With A Different Format

Sometimes switching from .zip to .7z or .rar can achieve better compression. 7-Zip’s .7z format often shrinks files more aggresively than standard zip. This might reduce a 30 MB folder to under 20 MB, fitting Outlook’s limit.

  1. Install 7-Zip.
  2. Right-click your folder and select “7-Zip > Add to archive.”
  3. Under “Archive format,” choose “7z.”
  4. Set compression level to “Ultra” for maximum size reduction.
  5. Click OK. The resulting file may be smaller than a standard zip.
  6. Attach the .7z file to your Outlook email.

Note that recipients need 7-Zip or WinRAR to extract .7z files. Most modern systems do not natively support this format. Include a note with download instructions if necessary.

Common Errors When Sending Large Zip Files

Even with the right method, you might encounter issues. Here are frequent problems and how to fix them.

Error: “File Exceeds Size Limit”

This appears when your attachment is over 20–25 MB. Solution: Use OneDrive, split the file, or switch to a cloud link. Do not try to attach the file repeatedly—Outlook will reject it every time.

Error: “Zip File Blocked By Security”

Some email servers block .zip attachments to prevent malware. Solution: Rename the file extension to .zxp or .zipx temporarily, or use a password-protected zip. Alternatively, upload to OneDrive and share the link.

Error: “Recipient Cannot Open The Zip”

This often happens when the zip is corrupted during upload or download. Solution: Always test the zip file after creation by extracting it yourself. If you split the file, ensure all parts are sent and named correctly.

Best Practices For Sending Large Files In Outlook

Follow these guidelines to ensure smooth delivery every time.

  • Always compress before attaching, even if you use a cloud link. Smaller files upload faster.
  • Use descriptive file names. Avoid spaces or special characters that might break links.
  • Check recipient’s email size limits. Some corporate accounts restrict incoming attachments to 10 MB.
  • Include instructions in the email body if you use split archives or alternative formats.
  • Set expiration dates on cloud links to avoid stale files lingering online.
  • Test the download link yourself before sending to confirm it works.

Frequently Asked Questions

Can I send a zip file larger than 25 MB in Outlook?

Yes, but not as a direct attachment. You must use OneDrive, SharePoint, or a third-party service to generate a download link. Outlook will automatically suggest uploading to OneDrive when you try to attach a file that is too large.

What is the maximum size for a zip file in Outlook?

Outlook’s attachment limit is 20 MB for Exchange accounts and 25 MB for Microsoft 365. However, many email providers enforce smaller limits. To be safe, keep attachments under 10 MB or use a cloud link for anything larger.

How do I compress a zip file to send in Outlook?

Right-click the folder, select “Send to > Compressed (zipped) folder.” If the result is still too large, use 7-Zip with ultra compression, or split the archive into smaller volumes. Alternatively, upload the original zip to OneDrive and share the link.

Why does Outlook say my zip file is too large even after zipping?

Zipping does not always reduce file size significantly, especially for already-compressed formats like JPEG, MP4, or PDF. Check the zip file’s properties—if it is still over 20 MB, use a cloud sharing method instead.

Can I password-protect a zip file before sending via Outlook?

Yes. Use 7-Zip or WinRAR to set a password during compression. Then attach the file or upload it to OneDrive. Share the password in a separate email or message for security. Note that password-protected zips may still be blocked by some email filters.

Final Tips For Success

Mastering how to send large zip files in outlook saves time and frustration. Always test your method with a small file first to ensure the recipient can access it. If you send sensitive data, use encryption and expiring links. Remember that cloud sharing is generally faster and more reliable than splitting files into multiple emails.

For regular large file transfers, consider upgrading your OneDrive storage or using a dedicated file transfer service. Outlook’s integration with Microsoft 365 makes OneDrive the most seamless option, but third-party tools work well for occasional use. Keep your recipients informed about how to download and extract the files, and you will avoid support requests.

By following the steps in this guide, you can confidently send any zip file, regardless of size. Whether you choose cloud links, split archives, or alternative compression, the key is to work within Outlook’s limitations while ensuring your data arrives intact. Start with the OneDrive method—it is the easiest and most secure for most users.