February 2024
Beginner to intermediate
304 pages
9h 13m
Japanese
Content preview from 実務で使える メール技術の教科書 基本のしくみからプロトコル・サーバー構築・送信ドメイン認証・添付ファイル・暗号化・セキュリティ対策まで
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Let's learn about email technology!
なお、これらの応答コードがすべて使用されるわけではありません。SMTP
サーバーによって異なる可能性がありますし、応答コードに加えて、そのエ
ラーの詳細を示す文面が追加されることもあります。
■ メールソフトを使わずに SMTP で送信する
応答コードの概要を理解したうえで、SMTP を使ってメールがどのように
送信されるのか（メールソフトの裏側でどのようなやり取りが行われているの
か）、具体的な内容を解説します。
SMTP コマンドでメールを送信するには、次の手順で操作します。
1．メールサーバーに接続する
2．送信者を指定する
3．受信者を指定する
4．タイトルや本文などを入力する
5．メールを送信する
最初に、メールサーバーに接続します。Telnet プロトコルで接続したら、
「HELO」に続けてクライアント（送信者）のホスト名を指定します。ここで
指定したホスト名が、メールが経由したメールサーバーのログ情報としてメー
ルのヘッダー部分に追加されます。
この「HELO」は一般的な英語の「HELLO」より L が 1 つ少ないですが、こ
ういう決まりです。拡張仕様を使って送る場合は「EHLO」というコマンド
※3
を使うこともあります。
メールサーバー側で準備ができていれば、「250」という応答コードが返っ
てきます。この「250」というのは正常に通信できたことを意味しています。
HELO masuipeo.com
250 mail.example.com ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.