Three standard email security protocols are used to secure email transmission: Secure Sockets Layer (SSL), Transport Layer Security (TLS) and STARTTLS. Because insecure email is a common attack vector for cybercriminals, it’s critical to use email security protocols like SSL/TLS and STARTTLS. Without this measure, users subject their emails and the sensitive data they contain to the possibility of interception, theft and email domain spoofing. With SSL/TLS or STARTTLS in place, cybercriminals who intercept an email can’t unencrypt it without the keys to decode it, which only the email server and client have.