Fact Check: Can Outlook send large email attachments?
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.
Outlook along with pretty much all other email providers limit your email attachment size limit to around 20 - 25 MB. It's fairly easy to hit that size limit. You can always compress and create a .zip file with your files to try and fit them within the limit. But now you are creating more and more steps to simply send an email. We discussed in greater detail here, on why it's not the best idea to send files in email attachments.