awssdk for ruby send email with attaching file

ses_file_send.rb

# -*- coding: utf-8 -*-
require 'aws-sdk'

# ACCESS_KEYとSECRET_KEYを定義します
ACCESS_KEY = 'YOUR_ACCESS_KEY'
SECRET_KEY = 'YOUR_SECRET_KEY'

# 送信メールの本文を作成します
body = 'Sample email attaching file.'
# ファイルを読み込みbase64フォーマットにエンコードします
file_path = 'path_to_attach_file.png'
filecontent = File.read(file_path)
encodedcontent = [filecontent].pack("m")

# 送信用のメッッセージを作成します
marker = "AWSSESTESTSENDING"
mailtext =<<EOF
From: sender@domain.com
To: receipient@domain.com
Subject: A Sample Email
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=#{marker}

--#{marker}
Content-Type: text/plain
Content-Transfer-Encoding:8bit

#{body}

--#{marker}
Content-Type: image/png; name=\"#{file_path}\"
Content-Transfer-Encoding:base64
Content-Disposition: attachment; filename="#{file_path}"

#{encodedcontent}

--#{marker}--

EOF

# AWSの認証を行い、テストメールを送信します
ses = AWS::SimpleEmailService.new(:access_key_id => ACCESS_KEY,:secret_access_key => SECRET_KEY)
ses.send_raw_email(mailtext)