A thing you should know if you are using multiple email accounts with `git send-email`

In some case, we need to send patches that made by other people instead. git send-email command can know this situation by itself by comparing the commit author information and mail sender’s information. In that case, git send-email automatically add From: line pointing the real author of the patch in the body of the mail so that maintainers applying the patches can set the author information correctly. For example, if “Alice alice@abc.