Linux - send mail through SMTP

fromhost (helo 後面跟的 domainname)
mail from (寄信人)
rcpt to (收信人)

Yip@localpc:~> telnet mailsvr 25
Trying 123.123.123.123...
Connected to mailsvr.
Escape character is '^]'.
220 mailsvr.domain.com ESMTP Sendmail 8.8.8/8.8.8; Thu, 21 May 1998 20:45:51 +0800 (CST)
helo localpc
250 mailsvr.domain.com Hello Yip@localpc.domain.com [140.116.72.74], pleased to meet you
mail from:
250 ... Sender ok
rcpt to:
250 ... Recipient ok
data
354 Enter mail, end with "." on a line by itself
mail from telnet mailsvr port 25
.
250 UAA02587 Message accepted for delivery
quit

在 rcptmailsvr 收到的信件如下

From Yip@mailsvr.domain.com Thu May 21 20:36:29 1998
Received: from mailsvr.domain.com (mailsvr [123.123.123.123])
by rcptmailsvr.domain.com (8.8.5/8.8.5) with ESMTP id UAA05162
for ; Thu, 21 May 1998 20:36:29 +0800 (CST)
Received: from localpc (Yip@localpc.domain.com [140.116.72.74])
by mailsvr.domain.com (8.8.8/8.8.8) with SMTP id UAA02587
for ; Thu, 21 May 1998 20:46:32 +0800 (CST)
Date: Thu, 21 May 1998 20:46:32 +0800 (CST)
From: staff
Message-Id: <199805211246.uaa02587@mailsvr.domain.com>