fetch_emails_imap.rb

require "net/imap"
require "mail"

    def connect_to_mail_server (username , password,server ="imap.google.com",post=993,ssl=true)
        imap = Net::IMAP.new(server,port,ssl)
        imap.login(username,password)
        return imap        
    end

    def get_access_to_mail_boxes imap
        ["INBOX"].each do |box|
            begin
                imap.examine(mailbox)
            rescue 
                p "mailbox: #{box} is not exists"                
            end
        end
        return imap
    end

    def search_for_matched_emails imap
        message_ids = []
        ["search","words"].each do |word|
            message_ids << imap.search([word,"BODY"])
        end
        message_ids.flatten!
        return message_ids
    end

    def handle_attachments mail
        mail.attachments.each do |a|
            #remember to escape slashes in filename to be store correctly
            file = File.open("/path_to_store_file_in/#{a.filename}","w+b")
            file.write(a.body.decoded)
            file.close()
        end
    end

    def fetch_emails message_ids
        message_ids.each do |id|
            body            = imap.fetch(messsage_id,"BODY[]")[0].attr["BODY[]"] #return the whole body
            mail            = Mail.new(body)
            html_part       = mail.html_part.decoded || "html part is empty"
            plain_part      = mail.plain_part.decoded || "html part is empty"
            mail_subject    = mail.subject || "message has no subject"
            form            = mail.from.first
            to              = mail.to.first
            #remember to escape slashes in mail subject to be store correctly
            file_name   = "path_to_store_file_in" +subject+ ".html"
            file        = File.open(file_name,"w+b")
            file.close
            handle_attachments(mail)
        end
    end

    
    imap        = connect_to_mail_server("< username >","<password>")
    imap        = get_access_to_mail_boxes(imap)
    message_ids = search_for_matched_emails(imap)
    fetch_emails message_ids

    imap.logout #to terminate the session with the mail server

    

    full_email_body = imap.fetch(messsage_id,"BODY[TEXT]")[0].attr["BODY[TEXT]"] #return the whole body plan text and html parts
    only_plain_part = imap.fetch(messsage_id,"BODY[1]")[0].attr["BODY[1]"] #return plan text part of the e-mail body
    only_html_part  = imap.fetch(messsage_id,"BODY[2]")[0].attr["BODY[2]"] #return HTML part of the e-mail body