Check the From header for inbound mail

まだ誰も着手していません。

# Use case

I have received spam email whose domain of MAIL FROM is valid and the EHLO host is also allowed by the SPF.
However, the From header in the body is not match the MAIL FROM command.

This is a clear clue of spam. We need to check this situation. I have read the doc of check.authorize_sender,
it can be only used for checking the From header for outbound mail.

# Your idea for a solution

One solution is to add an additional new check for the FROM header, and implement the check logic in the bodyCheck callback.

However, this solution need to add certain configure in the configure file.

I suggest to write a fix check function in the mgspipeline or check_runner and make this as default check so that there is no need to add new configuration.

- [x] I'm willing to help with the implementation

まず check.authorize_sender のドキュメントを読み、issue で言及されている bodyCheck callback、mgspipeline、check_runner のエントリポイントを見つけます。受信した MAIL FROM と From headers を比較できる場所を特定し、意図されたデフォルトの check が追加設定なしで不一致を検出することを確認します。

索引モデルが issue の本文から書いたものです。