Manual:$wgUserEmailUseReplyTo/ja

詳細
に true が設定されている場合、利用者間のメール内で、送信者である利用者のメールアドレスを　From 行に直接記載するのではなく、Reply-To ヘッダーのみに記載します. Emails will appear to come from, but replies will be sent to the email address of the user sending the user-to-user email.

送信者である利用者のメールアドレスを From: 行に記載した方が、見た目がよく便利でもあります (これが既定の挙動です). There are several reasons why the default setting of false may not be desired and should be set to true. They are:


 * Putting the sending user's email address in the From: line doesn't as clearly differentiate user-to-user email (an email sent via the wiki) from directly sent messages (emails sent from an email client).
 * Another concern is that some mailers (like sSMTP) will use the From: address as the SMTP envelope sender (the generator of the email message). This behavior can cause email messages to be penalized for SPF violations (since the wiki server isn't authorized to send messages on behalf of other domains) e.g. anyuser@userdomain.com is not authorized to send mail on yourwiki.com domain.
 * MediaWiki installations on a shared server may fail to send user-to-user email due to spam prevention by disabling open mail relaying.

Setting to true may create a privacy issue, as bounces containing the recipient's email address may get returned to the server's sending user email address.