What are two security risks of sending confidential files via e-mail?

Traceability – It’s hard to determine where each email goes after it lands in the receiver’s inbox. Maybe he shares it with another colleague or maybe with a rival firm. From your desk, it’s hard to tell. Document Collaboration tools show you when, who and where text was changed seconds after the document was altered.
Security – The unsecure nature of email transmissions means that it is relatively simple for others to intercept, monitor, and tamper with documents. In Agilewords, we offer server-side encryption of the document.
Receipt – Depending on the email software you use, it’s also hard to tell if your colleague actually received the email. You can ask for a ‘confirmation’ to be sent back but some users turn this feature off. Other don’t know how to use it or simply won’t use it.
Viruses – Every time you share a business document by email, for example a legal contract, there is a risk that the response may contain a virus, Trojan horse, or malware. While your corporate firewall may catch most of these, all it takes is one to get through to do the damage.
Mobility – The popularity of memory sticks and USB drives means that documents are easily shared ‘offline’ as well. These ‘mobile’ documents can be read outside of corporate firewalls and shared without your permission whereas with Agilewords the actual file is never shared.

You could use either reason.