If you send emails in Ruby on Rails using Gmail as your SMTP, this little rake task will locate all the bounced emails, and reset those users email addresses automatically for you. Emails will remain in your inbox, but will be marked as read once handled. You may want to customize this to do something else, or be more rigorous in which emails ar…

emails.rake

 desc "Log in to the Gmail account and cleanse anyone who appears to have bounced"
  task :handle_bounces => :environment do
    require 'gmail'
    # Open a connection using your default smtp settings, could also define via YML or inline
    gmail = Gmail.connect!(ActionMailer::Base.smtp_settings[:user_name], ActionMailer::Base.smtp_settings[:password])
      # Find everything from the Gmail mailer daemon (unread only)
      emails = gmail.inbox.emails(:unread, :from => "mailer-daemon@googlemail.com", :subject => "Delivery Status Notification (Failure)")
      Rails.logger.info("Found #{emails.length} messages")
      emails.each do |email|
        # Gmail sets a header "X-Failed-Recipients", with each email that failed
        if !email.header["X-Failed-Recipients"].blank?
          bad_addresses = email.header["X-Failed-Recipients"].value.split(",")
          bad_addresses.each do |bad_addr|
            Rails.logger.info("looking for user with email: #{bad_addr}")
            # We assume you have a user model, but could also do whatever you want with the bad address here
            user = User.find_by_email(bad_addr)
            if user
              Rails.logger.info("Found: #{user.name}, resetting email address")
              user.email = nil # Reset the email, might vary for your use case
              user.save
            end
          end # close emails form header
          email.read! # Mark as read so we don't try to deal with it again next time
        end
      end # next email
    gmail.logout # done!
  end