It's less about how old it is, and more about how long it's been out of the general public consciousness. The courier font hasn't been (out of public view) in recent memory, so it doesn't have the same nostalgia factor.
It's an industry standard for screenplays, and I think we all remember having seen a screenplay in a movie or picture, with this weird monospace font.
You are certainly an outlier here.
Being a top level comment, I would assume my comment is read with at least the submission title in mind, as that was my intention. I was noting that I initially interpreted it as referring to Courier MTA / IMAP (and referenced IMAP servers to distinguish which Courier I was referring to).
So, to be very clear since apparently event my clarifications are being misconstrued, the courier font has been in public consciousness for as long as I can remember. I believe the courier MTA is not in the public consciousness any more. If this submission, titled "Courier Prime: It’s Courier, Just Better" was talking about mail servers (specifically, original courier and a cleaned up fork of courier as the title would theoretically allude to), then that would have been a cool blast from the past. It's not about mail servers being things of the past, mail servers was just used as a way to explain what other courier I thought it was originally referring to.
If IMAP is viewed as nostalgia install postfix/dovecot on something and play around.
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.