require 'net/smtp'
 
message = <<MESSAGE_END
From: Private Person <me@fromdomain.com>
To: A Test User <test@todomain.com>
Subject: SMTP e-mail test
 
This is a test e-mail message.
MESSAGE_END
 
Net::SMTP.start('localhost') do |smtp|
 smtp.send_message message, 'me@fromdomain.com',
               'test@todomain.com'
end

Net::SMTP.start('mail.your-domain.com',
        25,
        'localhost',
        'username', 'password' :plain)

require 'net/smtp'
 
message = <<MESSAGE_END
From: Private Person <me@fromdomain.com>
To: A Test User <test@todomain.com>
MIME-Version: 1.0
Content-type: text/html
Subject: SMTP e-mail test
 
This is an e-mail message to be sent in HTML format
 
<b>This is HTML message.</b>
<h1>This is headline.</h1>
MESSAGE_END
 
Net::SMTP.start('localhost') do |smtp|
 smtp.send_message message, 'me@fromdomain.com',
               'test@todomain.com'
end

require 'net/smtp'
 
filename = "/tmp/test.txt"
# 读取文件并编码为base64格式
filecontent = File.read(filename)
encodedcontent = [filecontent].pack("m")  # base64
 
marker = "AUNIQUEMARKER"
 
body =<<EOF
This is a test email to send an attachement.
EOF
 
# 定义主要的头部信息
part1 =<<EOF
From: Private Person <me@fromdomain.net>
To: A Test User <test@todmain.com>
Subject: Sending Attachement
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=#{marker}
--#{marker}
EOF
 
# 定义消息动作
part2 =<<EOF
Content-Type: text/plain
Content-Transfer-Encoding:8bit
 
#{body}
--#{marker}
EOF
 
# 定义附件部分
part3 =<<EOF
Content-Type: multipart/mixed; name=\"#{filename}\"
Content-Transfer-Encoding:base64
Content-Disposition: attachment; filename="#{filename}"
 
#{encodedcontent}
--#{marker}--
EOF
 
mailtext = part1 + part2 + part3
 
# 发送邮件
begin
 Net::SMTP.start('localhost') do |smtp|
   smtp.sendmail(mailtext, 'me@fromdomain.net',
             ['test@todmain.com'])
 end
rescue Exception => e 
 print "Exception occured: " + e 
end