Guide
Outlook: “The file you’re attaching is bigger than the server allows”
Outlook shows it when your attachments add up to more than 20 MB on a personal e-mail account, or more than the limit of your Exchange server at work. Microsoft suggests sending a link instead: up to 5 GB here, without an account.
Why Outlook shows this message
| Personal e-mail account (IMAP, POP) | Over 20 MB of attachments, one file or several together |
|---|---|
| Work account (Exchange server) | Over the limit set by the administrator: 10 MB by default |
| What Microsoft suggests | Put the file in a shared location and send a link |
Sources: Microsoft Learn, Outlook help — October 2026.
How to send bigger
A TransferThing link
Drop the file here, paste the link into your message. Up to 5 GB, without an account for you or the recipient.
A OneDrive link
Outlook offers to share the file from OneDrive, up to 2 GB. It uses your OneDrive storage.
Raise the limit (personal account)
Microsoft describes a Windows registry setting, MaximumAttachmentSize, to change the 20 MB. Most providers still refuse very large messages.
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Frequently asked questions
What does “The file you’re attaching is bigger than the server allows” mean?
Your attachments exceed the limit Outlook applies to your account: 20 MB by default for a personal e-mail account, the administrator’s limit for an Exchange account.
Why does it appear with a file under 20 MB?
On an Exchange server, the default is 10 MB, all attachments together, and the administrator can set another value.
Can I raise the limit myself?
On a personal e-mail account, yes, with the Windows registry setting Microsoft describes. On a work account, only the Exchange administrator can.
How do I send the file anyway?
Do what the message suggests: send a link. Drop the file on TransferThing and paste the link into your message: up to 5 GB, without an account.
Does the recipient need an account?
Not for a TransferThing link: they download in their browser, without an account.
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