Return-Path: <user1@example.com>
From: uesr1 <user1@example.com>
To: Yamada Taro <yamada@example.com>,"user2@example.com" <user2@example.com>,
 "user3@example.com" <user3@example.com>,
	user4 desu <user4@example.com>
Subject: aaabbbccc123
Content-Type: text/plain

Hello.