Sähköpostin virheet

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Liittynyt: 07 Marras 2007 20:17

Sähköpostin virheet

Viesti Kirjoittaja eero »

ZMailer raportit selitettynä; Suomeksi

Olette tätä lukemassa todennäköisesti siksi, että saitte sähköpostissa kirjeen joka alkaa näin:

This is a collection of reports about email delivery
process concerning a message you originated.

Some explanations/translations for these reports
can be found at:
http://www.zmailer.org/delivery-report-decoding.html

ZMailer postivälitysohjelmisto tuottaa käsittelemilleen sanomille joissakin tilanteissa erilaisia raportteja, jotka se lähettää sanoman lähettäneeseen osoitteeseen.

Ajoittain tätä ohjelmistoa käyttävien järjestelmien ylläpidoille tulee kysymyksiä teemalla: "Mitä tämä tarkoittaa kielellä XYZ?"

Valitettavasti alkuperäistä Internetin postijärjestelmää luotaessa[1][2] maailma oli selkeästi vain amerikkalainen ja englanninkielinen. Niinpä silloin kielikysymyksiin ei varsinaisesti kiinnitetty huomiota.

Nyttemmin käytännössä on nähty, etteivät juuri ketkään (edes englanninkieliset ihmiset) yleensä ymmärrä, miksi jokin sanoma ei mene perille (tai että se on mennyt perille.) Tai että mitä ihmettä postia välittävät ohjelmistot koettavat kertoa sanoman lähettäneelle siitä sanomasta oudolla tekno-kielellään.

Raporttisanomat ovat rakenteisia sanomia[5], jonka osat ovat:

1. Saate-teksti
2. Muodollinen osa
3. Alkuperäisen sanoman otsikot, tai otsikot ja sisältö

Rakenteen tarkoituksena on ollut tukea postikäyttöliittymiä siten, että ne voivat esittää muodollisen osan sisällön käyttäjän haluamalla kielellä.[3]

Mikäili postikäyttöliittymänne ei tähän kykene, Teidän on aika kysyä sen valmistajalta, milloin siitä saa version joka kykenee.

Osoitekohtaisesti nämä raportit ovat neljää tyyppiä:

FAILED
Sanoman toimitus perille ei onnistunut jostain syystä

DELIVERED
Sanoman toimitus perille onnistui (ja sen lähettäjä oli pyytänyt tiedon onnistuneesta toimituksesta vastaanottajalle.

Tämä ei tarkoita että vastaanottaja olisi lukenut sanomaa!)

RELAYED
Sanoma on toimitettu eteenpäin järjestelmälle, joka itse ei kykene tuottamaan lähettäjän pyytämää positiivista toimituskuittausta (s.o. tämän kohdeosoitteen osalta ette tule saamaan DELIVERED kuittausta! Muita raportteja saattaa kyllä tulla.)

DELAYED
Sanomaa ei vielä ole saatu toimitettua perille, vaan se on jonossa raportin lähettävässä systeemissä.

Esimerkki 1:

To: sender@domain
From: The Post Office <postmaster@local.server>
Subject: Delivery reports about your email [FAILED(1)]
Date: Wed, 1 Mar 2000 15:20:53 +0200

[-- Liite #1 --]
[-- Tyyppi: text/plain, Koodaus: 7bit, Koko: 1.7K --]

This is a collection of reports about email delivery
process concerning a message you originated.

Some explanations/translations for these reports
can be found at:
http://www.zmailer.org/reports.html

FAILED:
<smtp some.server.dom user.name@some.server.dom 99>: ...\
expired after 3 days, problem was:
smtp; 500 (connect to some.server.dom [11.22.33.44|25|55.66.77.88|1879]: Connection refused)


FAILED:
<smtp other.server.dom user@other.server.dom 60000>: ...\
<<- RCPT To:<user@other.server.dom> ORCPT=rfc822;user@other.server.dom
->> 550 <user@other.server.dom>... Relaying denied

FAILED:
<smtp other.server.dom user@other.server.dom 60000>: ...\
<<- RCPT To:<user@other.server.dom> ORCPT=rfc822;user@other.server.dom
->> 552 <user@other.server.dom>... Unknown User

[ Poistettu toisen ja kolmannen liitteen kopiot tästä tekstinäytteestä. ]


[-- Liite #2 --]
[-- Type: message/delivery-status, Koodaus: 7bit, Koko: 0.5K --]

Reporting-MTA: dns; local.server
Arrival-Date: Wed, 1 Mar 2000 15:19:53 +0200
Local-Spool-ID: S92519AbQCANTx

Original-Recipient: rfc822;user.name@some.server.dom
Final-Recipient: RFC822;user.name@some.server.dom
Action: failed
Status: 5.4.1 (TCP/IP-connection failure)
Diagnostic-Code: smtp; 500 (connect to some.server.dom [11.22.33.44|25|55.66.77.88|1879]: Connection refused)
Remote-MTA: dns; somemx.server.dom (11.22.33.44|25|55.66.77.88|1879)
Last-Attempt-Date: Wed, 1 Mar 2000 15:20:53 +0200

Original-Recipient: rfc822;user@other.server.dom
Final-Recipient: RFC822;user@other.server.dom
Action: failed
Status: 5.1.1 (bad destination mailbox)
Diagnostic-Code: smtp; 550 (<user@other.server.dom>... Relaying denied)
Remote-MTA: dns; mx.third.dom (22.33.44.55|25|55.66.77.88|2345)
Last-Attempt-Date: Wed, 1 Mar 2000 15:20:53 +0200

Original-Recipient: rfc822;user@other.server.dom
Final-Recipient: RFC822;user@other.server.dom
Action: failed
Status: 5.1.1 (bad destination mailbox)
Diagnostic-Code: smtp; 550 (<user@other.server.dom>... Unknown User)
Remote-MTA: dns; mx.third.dom (22.33.44.55|25|55.66.77.88|2345)
Last-Attempt-Date: Wed, 1 Mar 2000 15:20:53 +0200

[-- Liite #3 --]
[-- Tyyppi: message/rfc822, Koodaus: 7bit, Koko: 0.2K --]

From: Sender <sender@domain>
To: user.name@some.server.dom
Cc: user@other.server.dom
Subject: demo
Date: Wed, 1 Mar 2000 15:19:53 +0200

demo

Selitykset 1: RFC 1894 Muodollisen osan kentät

Reporting-MTA:
Tunnistaa mikä palvelin tarkkaan ottaen tuotti tämän raportin. Kyseessä saattaa olla esimerkiksi klusterin komponentti, jolloin tämä osatieto pitää olla tarjolla jotta ongelmien ratkaisussa löydetään oikea järjestelmä.

Arrival-Date:
Raportoitavan sanoman saapumisaika järjestelmään.

Local-Spool-ID:
Järjestelmän sisäinen yksilöintitieto raportoitavalle sanomalle. Järjestelmäylläpitäjä tarvitsee tätä poimiakseen järjestelmälogeista tähän sanomaan liittyviä merkintöjä.

Original-Recipient:
Postikuljetusprotokollan (SMTP) ``Delivery Status Notification'' (DSN) alijärjestelmän ORCPT parametri, tai sen puutteessa, raportoivalle sanomavälitysjärjestelmälle annettu alkuperäinen osoite ennen kuin sitä on muokattu järjestelmän sisällä mitenkään.

Final-Recipient:
Osoite siinä muodossa, kuin järjestelmä koetti sitä käsitellä.

Joissakin tilanteissa tämä voi olla huomattavasti erilainen, kuin alkuperäinen osoite -- siksi tuo ``Original-Recipient:''
Action:
Yksi seuraavista: DELIVERED/DELAYED/RELAYED/FAILED

Suomeksi suunnilleen: Toimitettu / Viivästynyt / Välitetty / Epäonnistunut

Kertoo mitä sanomalle on tapahtunut:

FAILED
Sanoman toimitus perille ei onnistunut jostain syystä

DELIVERED
Sanoman toimitus perille onnistui (ja sen lähettäjä oli pyytänyt tiedon onnistuneesta toimituksesta vastaanottajalle.

Tämä ei tarkoita että vastaanottaja olisi lukenut sanomaa!)

RELAYED
Sanoma on toimitettu eteenpäin järjestelmälle, joka itse ei kykene tuottamaan lähettäjän pyytämää positiivista toimituskuittausta (s.o. tämän kohdeosoitteen osalta ette tule saamaan DELIVERED kuittausta! Muita raportteja saattaa kyllä tulla.)

DELAYED
Sanomaa ei vielä ole saatu toimitettua perille, vaan se on jonossa raportin lähettävässä systeemissä.

Status:
Numeerinen ``laajennettu tilakoodi'', jota luokittelee hieman tarkemmin, mitä viestin käsittelyssä tapahtui.

Käyttäjän postikäyttöliittymäohjelman (ns. ``MUA'') pitäisi käyttää tätä koodia kertoakseen käyttäjän haluamalla kielellä, mistä oikein on kyse.

Diagnostic-Code:
Mahdollinen etäjärjestelmän tuottama karkeampi (vanhempi) koodi ja siihen liittyvä tekstisanoma koskien viestin/osoitteen kohtelua.

Remote-MTA:
Esiintyessään kertoo minkä etäjärjestelmän kanssa tehdyn protokollavaihdon seurauksena yllä mainitut ``Diagnostic-Code:'' tekstit saatiin.

Last-Attempt-Date:
Viimeisin ajankohta jolta vastaanottajaosoitteeseen liittyvä raportti on peräisin.

Mikäili raportissa on ``Action: DELAYED'', muita raportteja saattaa vielä tulla.

Selitykset 2: Oheistekstejä joita eri järjestelmät tapaavat antaa

User Unknown:
Unknown User:
No Such User:
Bad User:
Mailbox unavailable:
Vaihtelevia tapoja sanoa, että vaikka vastaanottava systeemi pitää osoitteen domain-osaa (@-merkin oikea puoli) paikallisena, mutta että se ei tunnista osoitteen paikallista osaa (@-merkin vasenta puolta) kuuluvaksi kenellekään systeemin käyttäjälle.

Connection Refused:
Connection Timed Out:
Yhteyttä kohdedomainia palvelevaan palvelimeen (mihinkään niistä, mikäili ne on määritelty oikein) ei ole onnistuttu saavuttamaan jonkin ajan kuluessa -- tyypillisesti 3-5 vuorokaudessa.

Relaying Denied:
This target address is not our MX service client:
You are not allowed to send to this address:
invalid address
... we do not relay
sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)
Postireititykseen kohdedomainille on määritelty mahdollisesti useampia laitteita ja sanomaa on koetettu kuljettaa sellaisen järjestelmän kautta, jolle ei ole kerrottu, että sen kautta saisi kuljettaa postia kohdedomainiin.

Kyseessä on konfigurointivirhe jossakin, joko kohdedomainin nimipalveludatassa, tai sähköpostin välityspalvelimessa.

Selitykset 3: Numeeristen ``Status:'' koodien teoria

Nämä numeeriset koodit on määritelty dokumentissa RFC 1893 [4].

Kuten mikään koodijoukko, nämäkään eivät ole täydellisiä kaikkiin käyttöihin, mutta ainakin nämä ovat paremmat kuin alkuperäinen SMTP[1] koodisto, jolla oli vain pari erilaista virhetilanteista kertovaa koodia.

Koodit näyttävät seuraavan kaltaisilta:

2.2.0
4.5.3
5.7.1

Yllä on siis kolme desimaalinumeroa joilla on pisteet väleissään.

Ensimmäinen koodinumero:

Tämä antaa karkean jaottelun koodille:

2.x.x
Onnistuminen

Onnistuminen kertoo että sanoma on välitetty onnistuneesti eteenpäin, mahdollisesti lopulliseen osoitteeseensa asti. Yksityiskohtaisempaa tietoa saa tutkimalla alikoodeja.

4.x.x
Tilapäinen toimitusvaikeus

Sanoman välitys ei ole onnistunut jonkin sellaisen syyn/tapahtuman takia, mitä pidetään todennäköisesti tilapäisenä. Sanoman välitys voi onnistua tulevaisuudessa.

5.x.x
Pysyvä virhe, toimitus mahdoton

"Pysyvä virhe" tarkoittaa tilanteita, joissa järjestelmän mielestä ei voida saavuttaa onnistunutta sanoman välitystä ilman että sanomaa muutetaan jotenkin. (Esimerkiksi osoitteessa on vikaa!)

Keskimmäinen koodinumero:

x.0.x
Muu, tai määrittelemätön tila

Tämä voi tarkoittaa mitä tahansa, jota ei ole onnistuttu luokittelemaan muihin koodeihin.

x.1.x
Osoite tila

"Osoite tila" kertoo lähettäjän tai vastaanottajan osoitteeseen liittyviä asioita. Se voi tarkoittaa syntaksia tai muuta kelvollisuutta.

Yleisesti lähettäjän pitää korjata osoite ja lähettää sanoma uudelleen.

x.2.x
Postilaatikon tila

"Postilaatikon tila" kertoo tavallisesti sanoman vastaanottajan postilaatikosta -- sellaisen olemassaolosta tai puutteesta.

Mikäili kyseessä on virhe, lähettäjän pitänee korjata osoitteeseen päässyt kirjoitusvirhe.

x.3.x
Postijärjestelmän tila

Tämä on yleiskoodisto postivälitysjärjestelmä koskeville sanomille.

x.4.x
Verkkoyhteys ja reititys tila

Nämä koodit kertovat välitysjärjestelmästä itsestään, tai sen sen kokemista asioista erilaisissa tietokannoissa.

x.5.x
Postin kuljetusprotokollan tila

Postin kuljetusprotokollan tilakoodit kertovat laajasta joukosta ongelmia sanoman siirron aikana. Nämä sisältävät monenlaisia ongelmia jotka johtuvat järjestelmien toteutusten ongelmista, yhteysongelmista, jne.

Osapuolia tässä ongelmaviidakossa on todella paljon.

x.6.x
Sanoman sisältö, tai media tila

Nämä liittyvät sanoman sisällön välittämiseen mahdollisesti tarvittavien käännösten tai muunnosten tekemiseen, sekä mahdollisiin ongelmiin tunnistamattomien lähdemuotojen käsittelyssä.

Sanoman sisältö ja media asiat ovat ongelma-alue jossa molempien, sekä lähettäjän että vastaanottajan, tulee käyttää yhteensopivia sisältötyyppejä.

x.7.x
Salaus-, Turvallisuus-, tai menettelytapatila

Näillä kerrotaan turvallisuus ja menettelytapa-asioihin liittyvistä vastaanottajakohtaisista tai järjestelmäkohtaisista suodatus ja kryptografia asioista.

Tavallisin näistä "5.7.1" joka viittaa yllä kerrottavaan sanoman välittämisestä kieltäytymiseen.

Kolmas koodinumero:

Kolmas koodinumero (x.x.N) riippuu täydellisesti keskimmäisestä koodinumerosta. Näiden luettelo on pitkä, eikä sitä siksi ole haluttu ottaa tähän dokumenttiin.


Lisää englanniksi:

Enhanced Mail System Status Codes

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

1. Overview

There currently is not a standard mechanism for the reporting of mail
system errors except for the limited set offered by SMTP and the
system specific text descriptions sent in mail messages. There is a
pressing need for a rich machine readable status code for use in
delivery status notifications [DSN]. This document proposes a new
set of status codes for this purpose.

SMTP [SMTP] error codes have historically been used for reporting
mail system errors. Because of limitations in the SMTP code design,
these are not suitable for use in delivery status notifications.
SMTP provides about 12 useful codes for delivery reports. The
majority of the codes are protocol specific response codes such as
the 354 response to the SMTP data command. Each of the 12 useful
codes are each overloaded to indicate several error conditions each.
SMTP suffers some scars from history, most notably the unfortunate
damage to the reply code extension mechanism by uncontrolled use.
This proposal facilitates future extensibility by requiring the
client to interpret unknown error codes according to the theory of
codes while requiring servers to register new response codes.

The SMTP theory of reply codes partitioned in the number space such a
manner that the remaining available codes will not provide the space
needed. The most critical example is the existence of only 5
remaining codes for mail system errors. The mail system
classification includes both host and mailbox error conditions. The
remaining third digit space would be completely consumed as needed to
indicate MIME and media conversion errors and security system errors.

A revision to the SMTP theory of reply codes to better distribute the
error conditions in the number space will necessarily be incompatible
with SMTP. Further, consumption of the remaining reply-code number



Vaudreuil Standards Track [Page 1]

RFC 1893 Mail System Status Codes January 1996


space for delivery notification reporting will reduce the available
codes for new ESMTP extensions.

The following proposal is based on the SMTP theory of reply codes.
It adopts the success, permanent error, and transient error semantics
of the first value, with a further description and classification in
the second. This proposal re-distributes the classifications to
better distribute the error conditions, such as separating mailbox
from host errors.

2. Status Codes

This document defines a new set of status codes to report mail system
conditions. These status codes are intended to be used for media and
language independent status reporting. They are not intended for
system specific diagnostics.

The syntax of the new status codes is defined as:

status-code = class "." subject "." detail
class = "2"/"4"/"5"
subject = 1*3digit
detail = 1*3digit

White-space characters and comments are NOT allowed within a status-
code. Each numeric sub-code within the status-code MUST be expressed
without leading zero digits.

Status codes consist of three numerical fields separated by ".". The
first sub-code indicates whether the delivery attempt was successful.
The second sub-code indicates the probable source of any delivery
anomalies, and the third sub-code indicates a precise error
condition.

The codes space defined is intended to be extensible only by
standards track documents. Mail system specific status codes should
be mapped as close as possible to the standard status codes. Servers
should send only defined, registered status codes. System specific
errors and diagnostics should be carried by means other than status
codes.

New subject and detail codes will be added over time. Because the
number space is large, it is not intended that published status codes
will ever be redefined or eliminated. Clients should preserve the
extensibility of the code space by reporting the general error
described in the subject sub-code when the specific detail is
unrecognized.




Vaudreuil Standards Track [Page 2]

RFC 1893 Mail System Status Codes January 1996


The class sub-code provides a broad classification of the status.
The enumerated values the class are defined as:

2.X.X Success

Success specifies that the DSN is reporting a positive delivery
action. Detail sub-codes may provide notification of
transformations required for delivery.

4.X.X Persistent Transient Failure

A persistent transient failure is one in which the message as
sent is valid, but some temporary event prevents the successful
sending of the message. Sending in the future may be successful.

5.X.X Permanent Failure

A permanent failure is one which is not likely to be resolved by
resending the message in the current form. Some change to the
message or the destination must be made for successful delivery.

A client must recognize and report class sub-code even where
subsequent subject sub-codes are unrecognized.

The subject sub-code classifies the status. This value applies to
each of the three classifications. The subject sub-code, if
recognized, must be reported even if the additional detail provided
by the detail sub-code is not recognized. The enumerated values for
the subject sub-code are:

X.0.X Other or Undefined Status

There is no additional subject information available.

X.1.X Addressing Status

The address status reports on the originator or destination
address. It may include address syntax or validity. These
errors can generally be corrected by the sender and retried.

X.2.X Mailbox Status

Mailbox status indicates that something having to do with the
mailbox has cause this DSN. Mailbox issues are assumed to be
under the general control of the recipient.






Vaudreuil Standards Track [Page 3]

RFC 1893 Mail System Status Codes January 1996


X.3.X Mail System Status

Mail system status indicates that something having to do
with the destination system has caused this DSN. System
issues are assumed to be under the general control of the
destination system administrator.

X.4.X Network and Routing Status

The networking or routing codes report status about the
delivery system itself. These system components include any
necessary infrastructure such as directory and routing
services. Network issues are assumed to be under the
control of the destination or intermediate system
administrator.

X.5.X Mail Delivery Protocol Status

The mail delivery protocol status codes report failures
involving the message delivery protocol. These failures
include the full range of problems resulting from
implementation errors or an unreliable connection. Mail
delivery protocol issues may be controlled by many parties
including the originating system, destination system, or
intermediate system administrators.

X.6.X Message Content or Media Status

The message content or media status codes report failures
involving the content of the message. These codes report
failures due to translation, transcoding, or otherwise
unsupported message media. Message content or media issues
are under the control of both the sender and the receiver,
both of whom must support a common set of supported
content-types.

X.7.X Security or Policy Status

The security or policy status codes report failures
involving policies such as per-recipient or per-host
filtering and cryptographic operations. Security and policy
status issues are assumed to be under the control of either
or both the sender and recipient. Both the sender and
recipient must permit the exchange of messages and arrange
the exchange of necessary keys and certificates for
cryptographic operations.





Vaudreuil Standards Track [Page 4]

RFC 1893 Mail System Status Codes January 1996


3. Enumerated Status Codes

The following section defines and describes the detail sub-code. The
detail value provides more information about the status and is
defined relative to the subject of the status.

3.1 Other or Undefined Status

X.0.0 Other undefined Status

Other undefined status is the only undefined error code. It
should be used for all errors for which only the class of the
error is known.

3.2 Address Status

X.1.0 Other address status

Something about the address specified in the message caused
this DSN.

X.1.1 Bad destination mailbox address

The mailbox specified in the address does not exist. For
Internet mail names, this means the address portion to the
left of the "@" sign is invalid. This code is only useful
for permanent failures.

X.1.2 Bad destination system address

The destination system specified in the address does not
exist or is incapable of accepting mail. For Internet mail
names, this means the address portion to the right of the
"@" is invalid for mail. This codes is only useful for
permanent failures.

X.1.3 Bad destination mailbox address syntax

The destination address was syntactically invalid. This can
apply to any field in the address. This code is only useful
for permanent failures.

X.1.4 Destination mailbox address ambiguous

The mailbox address as specified matches one or more
recipients on the destination system. This may result if a
heuristic address mapping algorithm is used to map the
specified address to a local mailbox name.



Vaudreuil Standards Track [Page 5]

RFC 1893 Mail System Status Codes January 1996


X.1.5 Destination address valid

This mailbox address as specified was valid. This status
code should be used for positive delivery reports.

X.1.6 Destination mailbox has moved, No forwarding address

The mailbox address provided was at one time valid, but mail
is no longer being accepted for that address. This code is
only useful for permanent failures.

X.1.7 Bad sender's mailbox address syntax

The sender's address was syntactically invalid. This can
apply to any field in the address.

X.1.8 Bad sender's system address

The sender's system specified in the address does not exist
or is incapable of accepting return mail. For domain names,
this means the address portion to the right of the "@" is
invalid for mail.

3.3 Mailbox Status

X.2.0 Other or undefined mailbox status

The mailbox exists, but something about the destination
mailbox has caused the sending of this DSN.

X.2.1 Mailbox disabled, not accepting messages

The mailbox exists, but is not accepting messages. This may
be a permanent error if the mailbox will never be re-enabled
or a transient error if the mailbox is only temporarily
disabled.

X.2.2 Mailbox full

The mailbox is full because the user has exceeded a
per-mailbox administrative quota or physical capacity. The
general semantics implies that the recipient can delete
messages to make more space available. This code should be
used as a persistent transient failure.







Vaudreuil Standards Track [Page 6]

RFC 1893 Mail System Status Codes January 1996


X.2.3 Message length exceeds administrative limit

A per-mailbox administrative message length limit has been
exceeded. This status code should be used when the
per-mailbox message length limit is less than the general
system limit. This code should be used as a permanent
failure.

X.2.4 Mailing list expansion problem

The mailbox is a mailing list address and the mailing list
was unable to be expanded. This code may represent a
permanent failure or a persistent transient failure.

3.4 Mail system status

X.3.0 Other or undefined mail system status

The destination system exists and normally accepts mail, but
something about the system has caused the generation of this
DSN.

X.3.1 Mail system full

Mail system storage has been exceeded. The general
semantics imply that the individual recipient may not be
able to delete material to make room for additional
messages. This is useful only as a persistent transient
error.

X.3.2 System not accepting network messages

The host on which the mailbox is resident is not accepting
messages. Examples of such conditions include an immanent
shutdown, excessive load, or system maintenance. This is
useful for both permanent and permanent transient errors.

X.3.3 System not capable of selected features

Selected features specified for the message are not
supported by the destination system. This can occur in
gateways when features from one domain cannot be mapped onto
the supported feature in another.








Vaudreuil Standards Track [Page 7]

RFC 1893 Mail System Status Codes January 1996


X.3.4 Message too big for system

The message is larger than per-message size limit. This
limit may either be for physical or administrative reasons.
This is useful only as a permanent error.

X.3.5 System incorrectly configured

The system is not configured in a manner which will permit
it to accept this message.

3.5 Network and Routing Status

X.4.0 Other or undefined network or routing status

Something went wrong with the networking, but it is not
clear what the problem is, or the problem cannot be well
expressed with any of the other provided detail codes.

X.4.1 No answer from host

The outbound connection attempt was not answered, either
because the remote system was busy, or otherwise unable to
take a call. This is useful only as a persistent transient
error.

X.4.2 Bad connection

The outbound connection was established, but was otherwise
unable to complete the message transaction, either because
of time-out, or inadequate connection quality. This is
useful only as a persistent transient error.

X.4.3 Directory server failure

The network system was unable to forward the message,
because a directory server was unavailable. This is useful
only as a persistent transient error.

The inability to connect to an Internet DNS server is one
example of the directory server failure error.

X.4.4 Unable to route

The mail system was unable to determine the next hop for the
message because the necessary routing information was
unavailable from the directory server. This is useful for
both permanent and persistent transient errors.



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A DNS lookup returning only an SOA (Start of Administration)
record for a domain name is one example of the unable to
route error.

X.4.5 Mail system congestion

The mail system was unable to deliver the message because
the mail system was congested. This is useful only as a
persistent transient error.

X.4.6 Routing loop detected

A routing loop caused the message to be forwarded too many
times, either because of incorrect routing tables or a user
forwarding loop. This is useful only as a persistent
transient error.

X.4.7 Delivery time expired

The message was considered too old by the rejecting system,
either because it remained on that host too long or because
the time-to-live value specified by the sender of the
message was exceeded. If possible, the code for the actual
problem found when delivery was attempted should be returned
rather than this code. This is useful only as a persistent
transient error.

3.6 Mail Delivery Protocol Status

X.5.0 Other or undefined protocol status

Something was wrong with the protocol necessary to deliver
the message to the next hop and the problem cannot be well
expressed with any of the other provided detail codes.

X.5.1 Invalid command

A mail transaction protocol command was issued which was
either out of sequence or unsupported. This is useful only
as a permanent error.

X.5.2 Syntax error

A mail transaction protocol command was issued which could
not be interpreted, either because the syntax was wrong or
the command is unrecognized. This is useful only as a
permanent error.




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X.5.3 Too many recipients

More recipients were specified for the message than could
have been delivered by the protocol. This error should
normally result in the segmentation of the message into two,
the remainder of the recipients to be delivered on a
subsequent delivery attempt. It is included in this list in
the event that such segmentation is not possible.

X.5.4 Invalid command arguments

A valid mail transaction protocol command was issued with
invalid arguments, either because the arguments were out of
range or represented unrecognized features. This is useful
only as a permanent error.

X.5.5 Wrong protocol version

A protocol version mis-match existed which could not be
automatically resolved by the communicating parties.

3.7 Message Content or Message Media Status

X.6.0 Other or undefined media error

Something about the content of a message caused it to be
considered undeliverable and the problem cannot be well
expressed with any of the other provided detail codes.

X.6.1 Media not supported

The media of the message is not supported by either the
delivery protocol or the next system in the forwarding path.
This is useful only as a permanent error.

X.6.2 Conversion required and prohibited

The content of the message must be converted before it can
be delivered and such conversion is not permitted. Such
prohibitions may be the expression of the sender in the
message itself or the policy of the sending host.

X.6.3 Conversion required but not supported

The message content must be converted to be forwarded but
such conversion is not possible or is not practical by a
host in the forwarding path. This condition may result when
an ESMTP gateway supports 8bit transport but is not able to



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downgrade the message to 7 bit as required for the next hop.

X.6.4 Conversion with loss performed

This is a warning sent to the sender when message delivery
was successfully but when the delivery required a conversion
in which some data was lost. This may also be a permanant
error if the sender has indicated that conversion with loss
is prohibited for the message.

X.6.5 Conversion Failed

A conversion was required but was unsuccessful. This may be
useful as a permanent or persistent temporary notification.

3.8 Security or Policy Status

X.7.0 Other or undefined security status

Something related to security caused the message to be
returned, and the problem cannot be well expressed with any
of the other provided detail codes. This status code may
also be used when the condition cannot be further described
because of security policies in force.

X.7.1 Delivery not authorized, message refused

The sender is not authorized to send to the destination.
This can be the result of per-host or per-recipient
filtering. This memo does not discuss the merits of any
such filtering, but provides a mechanism to report such.
This is useful only as a permanent error.

X.7.2 Mailing list expansion prohibited

The sender is not authorized to send a message to the
intended mailing list. This is useful only as a permanent
error.

X.7.3 Security conversion required but not possible

A conversion from one secure messaging protocol to another
was required for delivery and such conversion was not
possible. This is useful only as a permanent error.







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X.7.4 Security features not supported

A message contained security features such as secure
authentication which could not be supported on the delivery
protocol. This is useful only as a permanent error.

X.7.5 Cryptographic failure

A transport system otherwise authorized to validate or
decrypt a message in transport was unable to do so because
necessary information such as key was not available or such
information was invalid.

X.7.6 Cryptographic algorithm not supported

A transport system otherwise authorized to validate or
decrypt a message was unable to do so because the necessary
algorithm was not supported.

X.7.7 Message integrity failure

A transport system otherwise authorized to validate a
message was unable to do so because the message was
corrupted or altered. This may be useful as a permanent,
transient persistent, or successful delivery code.

4. References

[SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821,
USC/Information Sciences Institute, August 1982.

[DSN] Moore, K., and G. Vaudreuil, "An Extensible Message Format for
Delivery Status Notifications", RFC 1894, University of
Tennessee, Octel Network Services, January 1996.

5. Security Considerations

This document describes a status code system with increased
precision. Use of these status codes may disclose additional
information about how an internal mail system is implemented beyond
that currently available.

6. Acknowledgments

The author wishes to offer special thanks to Harald Alvestrand, Marko
Kaittola, and Keith Moore for their extensive review and constructive
suggestions.




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7. Author's Address

Gregory M. Vaudreuil
Octel Network Services
17060 Dallas Parkway
Suite 214
Dallas, TX 75248-1905

Voice/Fax: +1-214-733-2722
EMail: Greg.Vaudreuil@Octel.com









































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8. Appendix - Collected Status Codes

X.1.0 Other address status
X.1.1 Bad destination mailbox address
X.1.2 Bad destination system address
X.1.3 Bad destination mailbox address syntax
X.1.4 Destination mailbox address ambiguous
X.1.5 Destination mailbox address valid
X.1.6 Mailbox has moved
X.1.7 Bad sender's mailbox address syntax
X.1.8 Bad sender's system address

X.2.0 Other or undefined mailbox status
X.2.1 Mailbox disabled, not accepting messages
X.2.2 Mailbox full
X.2.3 Message length exceeds administrative limit.
X.2.4 Mailing list expansion problem

X.3.0 Other or undefined mail system status
X.3.1 Mail system full
X.3.2 System not accepting network messages
X.3.3 System not capable of selected features
X.3.4 Message too big for system

X.4.0 Other or undefined network or routing status
X.4.1 No answer from host
X.4.2 Bad connection
X.4.3 Routing server failure
X.4.4 Unable to route
X.4.5 Network congestion
X.4.6 Routing loop detected
X.4.7 Delivery time expired

X.5.0 Other or undefined protocol status
X.5.1 Invalid command
X.5.2 Syntax error
X.5.3 Too many recipients
X.5.4 Invalid command arguments
X.5.5 Wrong protocol version

X.6.0 Other or undefined media error
X.6.1 Media not supported
X.6.2 Conversion required and prohibited
X.6.3 Conversion required but not supported
X.6.4 Conversion with loss performed
X.6.5 Conversion failed





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X.7.0 Other or undefined security status
X.7.1 Delivery not authorized, message refused
X.7.2 Mailing list expansion prohibited
X.7.3 Security conversion required but not possible
X.7.4 Security features not supported
X.7.5 Cryptographic failure
X.7.6 Cryptographic algorithm not supported
X.7.7 Message integrity failure