When you send an email with a normal attachment (files from your PC), a copy of the file you selected is created and attached to your email. This copy is then saved on the mail server of both the sender as well as the recipient. This gradually takes up more and more storage space requiring you from time to time to delete old emails from your mailbox.
Attachments from myCloud look similar to normal attachments except no copies of the data are sent back and forth. Instead, a share link is sent that leads to your myCloud online storage. This prevents the sending process of your emails from slowing down and will also prevent too much storage space being taken up in your inbox. Additionally, this method of sharing attachments enables you to share an unlimited amount of data.
Figure: file sharing on myCloud.ch
If you also allow recipients to add files to those you already shared, these will also be stored securely in your myCloud account. This will enable you to quickly and easily share photos, videos, and other files with others.