The mailbox encoding standard assumes a mailbox name of the form
"<local-part>@<mail-domain>".
While the syntax allowed in each of these
sections varies substantially between the various mail internets, the
preferred syntax for the ARPA Internet is given in [RFC-822].
メールボックス指定標準は以下の形、
"<local-part>@<mail-domain>" のメール
ボックス名を想定する。
これらの各部分でゆるされる構文はいろいろなメール交換の組織により
そうとう違っている。
ARPAインターネットでの望ましい構文は[RFC-822]にある。
The DNS encodes the <local-part> as a single label, and encodes the
<mail-domain> as a domain name. The single label from the <local-part>
is prefaced to the domain name from <mail-domain> to form the domain
name corresponding to the mailbox. Thus the mailbox HOSTMASTER@SRI-
NIC.ARPA is mapped into the domain name HOSTMASTER.SRI-NIC.ARPA. If the
<local-part> contains dots or other special characters, its
representation in a master file will require the use of backslash
quoting to ensure that the domain name is properly encoded. For
example, the mailbox Action.domains@ISI.EDU would be represented as
Action\.domains.ISI.EDU.
DNS では <local-part>をひとつのラベルとしてコード化し、
ドメイン名として <mail-domain>をコード化する。
メールボックスに対応したドメイン名を構成するために、
<mail-domain> というドメイン名の前に
<local-part>というラベルが一つ付く。
それでメールボックスHOSTMASTER@SRI- NIC.ARPA は
ドメイン名HOSTMASTER.SRI-NIC.ARPA.に変換される。
もし<local-part>がドットなどの特殊文字を含むときは、
マスターファイル内ではバックスラッシュを前置して表現することで
ドメイン名が正しくコード化されるのを保証することが要求される。
例えば、メールボックス
Action.domains@ISI.EDUはAction\.domains.ISI.EDUと表現される。
One of the advantages of this method is that it decouples mail
destination naming from the hosts used to support mail service, at the
cost of another layer of indirection in the lookup function. However,
the addition layer should eliminate the need for
complicated "%", "!",
etc encodings in <local-part>.
この方法の利点のひとつはメールの宛先名をメールサービスを行うホストから
きり離していることである。
ただし、検索機能で一段の間接参照というコストをかけて。
しかしながら、追加した層は <local-part> のコーディングで、
複雑な"%", "!"の必要性も取りさるべきであった。
The essence of the method is that the <mail-domain> is used as a domain
name to locate type MX RRs which list hosts willing to accept mail for
<mail-domain>, together with preference values which rank the hosts
according to an order specified by the administrators for <mail-domain>.
この方法の本質は <mail-domain> が ドメイン名として、
タイプ MX の RRs を探すのに用いられることである。
MX RRs では
<mail-domain>宛のメールを受入れるホストの一覧とともに
<mail-domain> の管理者が指定した順序でホストを順位づける
ため優先値がある。
In this memo, the <mail-domain> ISI.EDU is used in examples, together
with the hosts VENERA.ISI.EDU and VAXA.ISI.EDU as mail exchanges for
ISI.EDU. If a mailer had a message for Mockapetris@ISI.EDU, it would
route it by looking up MX RRs for ISI.EDU. The MX RRs at ISI.EDU name
VENERA.ISI.EDU and VAXA.ISI.EDU, and type A queries can find the host
addresses.
このメモでは、<mail-domain>ISI.EDUを例に使い、
ホストVENERA.ISI.EDUとVAXA.ISI.EDU が ISI.EDUのメール交換を
受けもつとする。
Mockapetris@ISI.EDUへのメイルメッセージがあったら、
メーラは ISI.EDU の MX RRs を検索して、配信経路を決めるだろう。
ISI.EDUの MX RRs は VENERA.ISI.EDUとVAXA.ISI.EDU を指し、
A レコード問合せで、ホストアドレスを見つけだせる。
[翻訳は省略] In mailbox binding, the mailer uses the entire mail destination specification to construct a domain name. The encoded domain name for the mailbox is used as the QNAME field in a QTYPE=MAILB query.
Several outcomes are possible for this query:
1. The query can return a name error indicating that the mailbox does not exist as a domain name.
In the long term, this would indicate that the specified mailbox doesn't exist. However, until the use of mailbox binding is universal, this error condition should be interpreted to mean that the organization identified by the global part does not support mailbox binding. The appropriate procedure is to revert to exchange binding at this point.
2. The query can return a Mail Rename (MR) RR.
The MR RR carries new mailbox specification in its RDATA field. The mailer should replace the old mailbox with the new one and retry the operation.
3. The query can return a MB RR.
The MB RR carries a domain name for a host in its RDATA field. The mailer should deliver the message to that host via whatever protocol is applicable, e.g., b,SMTP.
4. The query can return one or more Mail Group (MG) RRs.
This condition means that the mailbox was actually a mailing list or mail group, rather than a single mailbox. Each MG RR has a RDATA field that identifies a mailbox that is a member of the group. The mailer should deliver a copy of the message to each member.
5. The query can return a MB RR as well as one or more MG RRs.
This condition means the the mailbox was actually a mailing list. The mailer can either deliver the message to the host specified by the MB RR, which will in turn do the delivery to all members, or the mailer can use the MG RRs to do the expansion itself.
In any of these cases, the response may include a Mail Information (MINFO) RR. This RR is usually associated with a mail group, but is legal with a MB. The MINFO RR identifies two mailboxes. One of these identifies a responsible person for the original mailbox name. This mailbox should be used for requests to be added to a mail group, etc. The second mailbox name in the MINFO RR identifies a mailbox that should receive error messages for mail failures. This is particularly appropriate for mailing lists when errors in member names should be reported to a person other than the one who sends a message to the list.