Support Portal - Attachment size exceeds the allowable limit" error when you add a large attachment to an email message in Outlook.

Attachment size exceeds the allowable limit" error when you add a large attachment to an email message in Outlook.

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. 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. For Best Practices, we suggest using files not large than 10 MB attachments.