"The two open-source apps, OpenVPN and the Sendmail Mail
Transfer Agent, are both extremely popular among business users.
According to a Veracode press release, its "A" rating indicates
that a software developer has "developed a secure application that
has been independently evaluated for software vulnerabilities
against industry standards."
"Security is a major concern for both projects. OpenVPN is a
widely used tool for creating point-to-point encrypted network
connections, and Sendmail MTA is the single most widely used
application of its type -- open-source or proprietary -- in use