Careful reading would have shown I was talking about the courier MTA, and used mailserver only to distinguish it from the other meanings of courier. I made no c

Careful reading would have shown I was talking about the courier MTA, and used mailserver only to distinguish it from the other meanings of courier. I made no claim that mailservers are not common. I'm well aware of dovecot and postfix. And also sendmail and cucipop. Some things are more common now than than they were in the past, and vice versa.