Simply put, email was not designed with any privacy or security in mind. In fact, there are essentially four points at which an email is vulnerable to compromise — the email sender’s device, the mail servers where it is stored, the network it travels across, and the email recipient’s device. 
You can password-protect your employees’ email accounts, but that works only if they regularly log out. A desktop machine open and logged in to an employee’s email client, or a mobile device without password protection, can leave email vulnerable to breach.
Even if you solve for those exposure points, though, the message still has to traverse a network to reach its recipient — and security and encryption here are vital. Moreover, email is briefly stored on several servers along its journey — many of which do not use security protocols to protect the data.
Many email programs also still use the outdated Secure Socket Layer (SSL) to secure the data over the Internet. And as the National Institute of Standards and Technology (NIST) explains, the US government’s position is that even the most updated version of Secure Socket Layer — the now nearly two-decade-old SSL 3.0 — is vulnerable to attack from hackers.
A federal government-caliber digital fax service, by contrast, provides protection for organizations of all sizes against these inherent weak points in email.
For example, the right digital fax service keeps all inbound and outbound faxes protected on a secure, password-protected website. In other words, when an employee in your company receives a digital fax by email, the email itself contains only a message that there is a fax waiting, along with a secure URL in the message. When the employee clicks that link, she is required to enter her digital fax PIN to access the fax.
Also, whereas many email programs still use the outdated and vulnerable SSL for email security, the best-in-class digital fax services use the most advanced version of the Transport Layer Security protocol, TLS 1.2.
Of course, many digital fax services do not employ TLS encryption — so this should be a key factor in selecting the right digital fax provider.