Mandrillapp invalid sender characters

mandrillapp_invalid_sender_characters.rb

# I was encountering this exception: Net::SMTPServerBusy: 401 4.1.7 Bad sender address syntax
# First I searched to see if there's any documentation around this issue but didn't find anything,
# so I wrote this snippet to find those invalid characters.

require 'mail'

Mail.defaults do
  delivery_method :smtp, {
    port: 25,
    address: "smtp.mandrillapp.com",
    user_name: ENV["MANDRILL_USERNAME"],
    password: ENV["MANDRILL_PASSWORD"]
  }
end

(32..255).each_with_object([]) do |codepoint, invalid_chrs|
  chr = codepoint.chr
  begin
    Mail.deliver do
      to      ENV["MYEMAIL"]
      from    "John Doe #{chr} <john@doe.com>"
      subject 'A transactional email from Mandrill!'
    end
  rescue Net::SMTPServerBusy
    invalid_chrs.push(chr)
  end
end

# => ["\"", "(", ",", ":", ";", "<", ">", "["]

Thank you for this, you have probably saved me a few hours and an headache.

i added this inside ApplicationMailer:

  def mail(headers = {}, &block)
    if block_given?
      super
    else
      # https://gist.github.com/hmnhf/da95ecd81240bbe96836
      # strip invalid characters from email headers
      [:from, :reply_to, :to].each do |param|
        name = headers.delete(param)
        email_match = name.match(/ <[^<>]+@[^<>]+>$/)
        if email_match
          sender = name.sub(email_match[0], '')
          headers[param] = "#{sender.tr('"(,:;<>[', '')} #{email_match[0]}"
        else
          headers[param] = name
        end
      end
      super(headers)
    end
  end

Thank you for the gist, saving a lot of time.