How to Send Large Files in Outlook

"Outlook" covers several different products, and each has its own limit. These are the typical figures:

Attachments are encoded for sending, which makes them roughly a third bigger, so the largest file you can actually attach is smaller than the headline number. And even if your Outlook accepts a large email, the recipient's mail server may reject it. Microsoft's support pages have the current limits for each product.

In the Outlook desktop app, a message that is too big triggers an error saying the attachment size exceeds the allowable limit. In Outlook.com and the new Outlook, you are offered a OneDrive upload instead. In a work account, a message can also bounce back later with a message too large notice from the server.

All of these mean the same thing: the email is bigger than a server along the way will carry. Trying again will not help; you need to send the file outside the email and put a link inside it.

1. In Outlook.com or the new Outlook, choose Attach and select the file.
2. If the file is too large to attach, Outlook offers to upload it to OneDrive and share it as a link.
3. Check the sharing permission. Links shared with people outside your organisation may need to be set to allow anyone with the link to view, depending on your settings.
4. Send the email as normal.

OneDrive links are handy if you already pay for Microsoft 365 storage. On a free Microsoft account, OneDrive storage is limited (5 GB at the time of writing), and that space is shared with your Outlook.com mailbox attachments. In many companies, IT policy blocks sharing OneDrive files with outside addresses, which is where the next option helps.

This works from every version of Outlook, including locked-down work accounts, because the email only contains a short link:

1. Open Share Large Video Files in your browser. There is no account to create.
2. Add your files, up to 1000 files or a folder, totalling up to 20 GB.
3. Choose Link, and add a password if the files are confidential.
4. Wait for the upload to finish with the tab open, then copy the link.
5. Paste it into your Outlook email and send.

Or choose Email and we send the download link to your recipients for you, after you confirm your address with a 6-digit code.

Your recipient downloads the original files from their browser, with no Microsoft account needed. The link expires after 1 day, after which the files are deleted. On the Transfers page you can see download counts, resend the email, extend the expiry or delete the transfer early. Before sending anything sensitive from a work account, check your company's policy on external file sharing, and read our security overview so you know what is and is not offered.

• Windows and Mac desktop: keep the upload tab open while you write your email, then paste the link when it is ready. Uploads are sent in chunks, and short connection drops are retried automatically while the tab stays open.
• Outlook for iPhone and Android: upload the file in Safari or Chrome first, copy the link, then switch to the Outlook app and paste it. On a phone you can also use the share sheet to send the link straight into a new email.
• Video files: zipping does not make video noticeably smaller. If a lower-quality copy is fine, export a smaller version from your video editor. A free video compressor is on the way on this site; for the full-quality original, a link is the better choice.
• Several attachments? Put them all in one transfer, or upload a folder, so your recipient gets one link rather than a chain of emails.

Also using Gmail? See how to send large files through Gmail.