By default , the maximum outgoing email size which includes the message and any attachments is 50 MB.
However at times, you may encounter the below error in Outlook even with attachment below 30 MB
The file you're attaching is bigger than the server allows. Try putting the file in a shared location and sending a link instead.
You receive this error message because Outlook 2013 and later versions have 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.
Below article will show the steps to modify the default attachment limit depend on the type of email account that you are using with Outlook.
To modify the default attachment limit size in Outlook 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:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\ x.0 \Outlook\Preferences
- The <x.0> placeholder represents your version of Office (16.0 = Office 2016, Office 2019, Office LTSC 2021, or Office 365, 15.0 = Office 2013).
- 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.