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 the gist, saving a lot of time.