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!
■ Postfix による送信メールの容量制限
メールの容量制限は受信側だけが対応すればよいわけではありません。
SMTP ではメールを転送するだけなので、データを保存する必要はありませ
んが、大容量のメールが送信されるとネットワークの帯域は占有してしまいま
す。
複数のメールサーバーを経由してメールが送信されることを考えると、メー
ルを送信するときにも制限をかけるべきだと考えられます。
そこで、SMTPサーバーにも容量制限の設定があります。たとえば、
Postfix で設定する場合は、設定ファイルの「main.cf」にて次のような項目
を追加します。
この「message_size_limit」が 1 通のメールの最大容量で、上記のように
10240000 を指定すると 10MB となります。
図 3-9
共有するメールボックス
ネットワークを占有すると
他の人がメールを送受信できなくなる
1人が多く使うと、
他の人に影響する
…
メールボックスメールボックスメールボックス
メールサーバー
/etc/postfix/main.cf
message_size_limit = 10240000
mailbox_size_limit = 51200000
virtual_mailbox_limit = 0
146
125-154̲mail̲NSM̲F2.indd146125-154̲mail̲NSM̲F2.indd146 2024/01/259:53 ...
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