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. メールは  から送信されたように見えますが、返信は従来の通り正しい宛先に届きます.

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). However, there are several reasons why this may not be desired:


 * Putting the sending user's email address in the From: line doesn't as clearly differentiate user-to-user email (sent via the wiki) from directly sent messages (such as those 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) as well. For open sites, this 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), as well as creating a privacy issue, as bounces containing the recipient's email address may get sent to the sending user.