Like many other companies there are some limitations in the size of an attachments in emails. There are a lot of free cloud hosting
like dropbox etc that you can safely upload your attachments to their space and share a link with the receive in an email.
In South Korea too you can find free cloud space for your files and attachments. For example www.naver.com offers free cloud. If you are sending an attachment to a Korean and you have a naver account you can use naver cloud for this purpase.
The following screenshot will help you with naver settings. As time goes on Naver might change the apperance of it's interface if what you see is
different please feel free to contact us and we will update this post.