Guide · updated
Attachment too large? How to send a big file
Your email won’t send, or it bounces back with an error. The reason is almost always the same: there’s a size limit on attachments, and you hit it sooner than you’d expect. This page covers the limits of the most common email services, why a file below the limit can still fail, and how to get a big file to its recipient.
Attachment limits in common email services
| Service | Maximum message size | What happens over the limit |
|---|---|---|
| Gmail | 25 MB | Gmail removes the attachment and adds a Google Drive link instead. |
| Outlook.com | 20 MB | The attachment can’t be added, or Outlook suggests a OneDrive link. |
| Microsoft 365 (work email) | 35 MBadmins can set 1–150 MB | The message bounces back with an error. |
The limits apply to the whole message, not just the file. At work, your administrator may have set a stricter limit – according to Microsoft, the default for Exchange accounts can be as low as 10 MB. Providers may change their limits, so check the sources at the end of this page for current figures.
Why doesn’t a 19 MB file fit a 20 MB limit?
Email was originally built for text. When you attach a photo, video or PDF, it is converted to text for sending (base64 encoding), which makes it roughly a third larger. Microsoft states in its own documentation that a message leaving the organisation grows by 33% because of this encoding.
In practice:
- A 20 MB limit fits a file of about 15 MB.
- A 25 MB limit fits a file of about 18 MB.
On top of that, the message only arrives if it fits both the sender’s and the recipient’s limit. Even if your service allows 35 MB, the recipient’s server may reject it if its own limit is lower.
Four ways to send a large file
1. Zip the file
Zipping shrinks text documents and spreadsheets considerably. Photos, videos and PDFs are usually already compressed, so zip barely helps with them.
2. Make photos or videos smaller
Phones and photo apps can reduce the size of a picture or video, but quality suffers – and often that won’t do. A photographer, a print shop or a doctor usually needs the original file.
3. Share a cloud storage link
Google Drive, OneDrive and Dropbox work, but come with their own hassles: the recipient needs the right sharing permissions, the file stays in the cloud until you remember to delete it, and it uses up your storage. The file is also stored in a form the provider can read.
4. Send it as an encrypted link with Liitetiedosto
With Liitetiedosto a large file travels as a link, and neither of you needs an account:
- Open Liitetiedosto and drop the file on the page. You can pick several files at once.
- Choose how long the link stays valid and how many times the file can be downloaded. Add a password if you like.
- Copy the link and paste it into an email, a text message or a chat.
- The recipient opens the link, and the file is decrypted in their browser.
The file is encrypted on your own device before upload, and the decryption key travels only in the link. We can’t see the contents of the file or its name. What does end-to-end encryption mean? When the link expires or the downloads are used up, the file is deleted.
Sources
- Google: Attach files in Gmail
- Microsoft: Send large files with Outlook
- Microsoft Learn: Exchange Online limits
Information checked on 15 October 2026.