Re: [9fans] pop3 before smtp

[Geoff Collyer <geoff@collyer.net>]

There are lots of things wrong with strict SMTP, such as the enforced
slowness due to its lock-step nature, but perhaps the most egregious
is that it enforces a 7-bit channel.  I used to think that this was
for the sake of long-dead PDP-10s, but it turns out to be for the
benefit of (CSnet?) people who wanted to run SMTP over plain old
un-error-corrected, un-flow-controlled serial lines without benefit of
TCP/IP underneath, and who feared that the high bit might be lost as a
parity bit (never mind that whole chunks of the message might be lost
due to lack of flow control, or garbled due to lack of error
correction).

So given that one expects there to be people who can only talk strict
821 SMTP, Content Transfers Encodings become necessary if one wants to
send 8-bit data, such as UTF-8.  So some of the MIME mess is directly
due to the failings of strict SMTP.  And that's just a bit of the
fall-out from SMTP's failings.