Re: SMTP server error message

[Stephen J. Turnbull]

Eli Zaretskii writes:
 > > From: "Stephen J. Turnbull" <address@hidden>
 > > Cc: address@hidden
 > > Date: Sat, 31 May 2014 23:47:07 +0900
 > > 
 > > Eli Zaretskii writes:
 > > 
 > >  >   451 4.0.0 Spam filter end message failed - server - license [slot 1]

Oops, should have investigated more carefully instead of going by
memory.  Here's the RFC 5321 definition of status code 451:

451     Requested action aborted: local error in processing

 > It's not coming from the list, though.  It comes from the SMTP server
 > my Emacs is talking to in order to send email.

Sorry, I shouldn't have mentioned the MTA policy or emacs-devel.
They're irrelevant since you're using smtpmail.

 > Are you saying that the SMTP server is trying to greylist me
 > personally?  Why would it want to do that?

Greylisting affects all incoming calls to the server, not just you.
If it's just you, it's not greylisting.

 > [greylisting timing] doesn't seem to match what I see:
 > It's my ISP's SMTP server.

OK, I just guessed entirely wrong.  Very sorry!  Between the
definition of 451, and those two facts, we can rule out greylisting.

451 means an intermittent problem at your ISP.  The "one broken node
in the cluster" hypothesis sounds plausible to me, but in any case
since the server is at your ISP, they should fix their server.  It's
not smtpmail, since the transaction is completing with a proper
response code, it's the server.

To save you (and maybe others) some grief, smtpmail could retry on any
status code matching "4[0-9][0-9]", that's what an SMTP client is
supposed to do.  Probably in most cases waiting a few seconds and
trying once should be enough when you're talking only to your ISP.