Adding a large attachment to an email message in Outlook 2013

This problem occurs for one of the following reasons, depending on the kind of email account that you are using.

For Internet email accounts using POP3, IMAP or HTTP

You receive this error message because Outlook 2013 has a default attachment size limit of 20 megabytes (20480 KB) for Internet email accounts. This limit prevents your computer from continually trying to upload very large attachments that exceed the limits of most Internet service providers. This limit applies whether you are adding one large attachment that is greater than 20 megabytes (MB) or several attachments whose sum total size is greater than 20 MB.

The steps to modify the default attachment limit depend on the type of email account that you are using with Outlook 2013.

Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 How to back up and restore the registry in Windows XP and Windows Vista

Resolution for Internet email accounts using POP3, IMAP or HTTP

warning: modifying the Windows registry can cause problems with your computer, it is recommended that you backup your system prior to making any changes.

To modify the default attachment limit size in Outlook 2013 for an Internet email account yourself, follow these steps: 
  1. Exit Outlook.
  2. Start Registry Editor.
  3. Locate and then select one of the following registry subkeys:

    Note Manually create the path in the registry if it does not currently exist.
  4. Add the following registry data under this subkey:

    Value type: DWORD
    Value name: MaximumAttachmentSize
    Value data: An integer that specifies the total maximum allowable attachment size. For example, specify 30720 (Decimal) to configure a 30-MB limit.
    • Specify a value of zero (0) if you want to configure no limit for attachments.
    • Specify a value that is less than 20 MB if you want to configure a limit that is less than the default 20 MB.
  5. Exit Registry Editor
  6. Start Outlook.