Why do I have to outline the texts in my design?
Fonts usually come with licenses that restrict them from being shared. It is better for you not to upload or share a font file with a customer.
You can convert the font(s) on your design to outline(s) before you send it to the customer. Therefore, the customer will be able to view the fonts without having to install the font file(s) on their computer.
For business cards, flyers and designs that need to be edited, make sure you provide the editable version in EPS & PDF formats. But remember to mention the details of the font(s) you used, and mention to them where they can buy the license for the font.