On 4/11/20 2:08 PM, antlists wrote:
Okay, it was a long time ago, and it was MS-Mail (Exchange's
predecessor, for those who can remember back that far), but I had an
argument with my boss. He was well annoyed with our ISP for complying
with RFC's because they switched to ESMTP and MS-Mail promptly broke.
I don't recall any RFC (from the time) stating that ESMTP was REQUIRED.
It may have been a SHOULD.
The ISP chose to make the change that resulted in ESMTP.
Also, I'm fairly sure that MS-Mail didn't include SMTP in any capacity.
It required an external MS-Mail SMTP gateway, which I Microsoft did
sell, for an additional cost.
The *ONLY* acceptable reason for terminating a connection is when you
recieve the command "BYE", so when Pipex sent us the command EHLO,
MS-Mail promptly dropped the connection ...
I'll agree that what you're describing is per the (then) SMTP state
machine. We have sense seen a LOT of discussion about when it is proper
or not proper to close the SMTP connection.
If the MS-Mail SMTP gateway sent a 5xy error response, it could see how
it could subsequently close the connection per protocol state machine.
Pipex, and I suspect other ISPs, had to implement an extended black list
of customers who couldn't cope with ESMTP.
If the MS-Mail SMTP gateway hadn't closed the connection and instead
just returned an error for the command being unknown / unsupported,
Pipex would have quite likely tried a standard HELO immediately after
getting the response.
Also, we're talking about the late '90s during the introduction of
ESMTP, which was a wild west time for SMTP.
--
Grant. . . .
unix || die
