A MailFetcher fecthing mails via IMAP and parsing it with Tmail. A enhanced module is included to fitler the mail by some condition and also dump the mail content and attachment to the file system.

MailFetcher.rb

require 'net/imap'
require 'tmail_mail_extension'

class MailFetcher
  cattr_accessor :email_download_path
  self.email_download_path = File.join(RAILS_ROOT, 'public','emails_download')
  
  def initialize(setting)
    @setting = setting
  end
  
  def fetch
    imap = Net::IMAP.new(@setting[:IMAP_HOST], @setting[:IMAP_PORT], true)
    imap.login(@setting[:LOGIN_EMAIL_USER_NAME], @setting[:LOGIN_EMAIL_PASSWORD])
    imap.select('inbox')
    imap.search(["UNSEEN"]).each do |id|
      source = imap.fetch(id, ['RFC822']).first.attr['RFC822']
      email = TMail::Mail.parse(source).extend ParsedEmail
      if email.should_fetch?(@setting[:EMAIL_FILTER_DATE_FROM], @setting[:EMAIL_FILTER_DATE_TO], @setting[:EMAIL_SUBJECT_KEY_WORDS])
        email.save_content(MailFetcher.email_download_path)
        EmailHistory.record_incoming email
        imap.store(id, "+FLAGS", [:Seen])
      end
    end
    imap.logout
  end
end

# An exhanced Email module to TMail Parse Result.
module ParsedEmail
  attr_reader :content_path

  def should_fetch?(form_date,to_date,key_words)
    return false if date < Date.parse(form_date)
    return false if date > Date.parse(to_date) + 1
    key_words.split(',').any? { |key_word| subject.include?(key_word) }
  end

  def should_reply_to
    email_pattern = /([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA -Z]\.)+[a-zA-Z]{2,9})/
    should_reply_to = reply_to 
    should_reply_to = from if reply_to.blank?
    (body_plain||body_html||'').gsub(email_pattern){ |email_in_body| should_reply_to = email_in_body}
    should_reply_to
  end
  
  def save_content(base_path)
    @content_path = File.join(base_path, should_reply_to, date.to_s(:db))
    FileUtils.makedirs(@content_path)
    File.open(File.join(@content_path,"email_text.html"),'w+') { |f| f << body_html } unless body_html.blank?
    File.open(File.join(@content_path,"email_text.txt"),'w+') { |f| f << body_plain } unless body_plain.blank?
    unless attachments.blank?
      File.open(File.join(@content_path,attachments.first.original_filename),'w+') do |f|
        f << attachments.first.gets(nil)
      end
    end
  end
end