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,
# 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

def check_if_char_is_invalid c
  @invalid_chars ||= []

  mail = Mail.deliver do
    to      ENV["MYEMAIL"]
    from    "John Doe #{c} <john@doe.com>"
    subject 'A transactional email from Mandrill!'
  end
  rescue Net::SMTPServerBusy
    puts "invalid char: #{c}"
    @invalid_chars.push(c).uniq!
end

(32..255).each { |x| check_if_char_is_invalid x.chr }

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