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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2
−
1
—
—
SMTPの通信
■ メールの送信、転送に使われる SMTP
SMTP は「Simple Mail Transfer Protocol」という名前の通り、「シンプ
ルにメールを転送するプロトコル」で、クライアント側からサーバー側に実行
してほしい要求を送信すると、それに対する返答が返ってきます。この要求を
SMTP コ マ ン ド（SMTP commands）、返 答 を SMTP 応 答（SMTP
replies）といいます。
これは、メールサーバーとメールソフトがチャットのようにやり取りしてい
る様子を思い浮かべるとよいでしょう。利用者が作成したメールを送信するた
めにメールサーバーに接続して SMTP コマンドを送信し、メールサーバーか
らの SMTP 応答を確認しながら、必要な SMTP コマンドを順次送信していま
す【図 2-4】。
メールソフトとメールサーバーの間で行われている SMTP のやり取りは、
Telnet というプロトコルを使って確認できます。Telnet で通信するには、
図 2-4
SMTP コマンドと SMTP 応答
SMTPコマンド
SMTPコマンド
SMTP応答
SMTP応答
SMTP応答
SMTPコマンド
63
059-080̲mail̲NSM̲F2.indd63059-080̲mail̲NSM̲F2.indd63 2024/01/259:402024/01/259:40
Let's learn about email technology!
Telne ...
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