However, it's a challenge to measure how many recipients are replying to those emails, as the email goes straight back to the sales rep. One solution was to create an email alias that forwards the email to both the sales rep and another mailbox. That mailbox has to be monitored manually...
This is for instance used in the SCRAM SASL mechanism to prevent man-in-the-middle attacks on the challenge-response exchange. Such uses of channel bindings for linking application-layer authentication to transport layer security requires that a man-in-the-middle should not be able to force the...