title: ActionMailer with SMTP - Bad recipient address syntax
body: <p>My user has email with this format: "-user-@domain.com". Mailgun validation succeeded but Rails couldn't send email to the address. I'm using SMTP with Mandrill.
  This is the error message: </p>
  
  <pre><code>/home/johnny/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/net/smtp.rb:948:in `check_response': 401 4.1.3 Bad recipient address syntax (Net::SMTPServerBusy)
  </code></pre>
  
  <p>Do you have any idea?</p>
  
  <p>Thanks in advance.</p>
  
  <p><strong>Updated:</strong></p>
  
  <p>This sample code (with valid SMTP configuration) would raise the error:</p>
  
  <pre><code>#!/usr/bin/env ruby
  require 'mail'
  
  options = {
      address:      "smtp.mandrillapp.com",
      port:     587,
      domain:     "mydomain.com",
      authentication:   "login",
      user_name:    "myemail@mydomain.com",
      password:     "mypassword",
      enable_starttls_auto: false
  }
  
  Mail.defaults do
      delivery_method :smtp, options
  end
  
  Mail.deliver do
      from 'valid.email@domain.com'
      to "-test-@domain.com"
      subject 'Testing sendmail'
      body 'Testing sendmail'
  end
  </code></pre>