title: 553 5.7.1 <mydomain>: Sender address rejected: not owned by user admin@mydomain.com
body: <p>In a rails4 application, I am trying to send emails by configuring smtp settings but I am getting the following error:</p>
  
  <blockquote>
    <p>553 5.7.1 : Sender address rejected: not owned by user
    admin@mydomain.com</p>
  </blockquote>
  
  <p>I am using the following settings:</p>
  
  <pre><code>config.action_mailer.delivery_method = :smtp
    ActionMailer::Base.smtp_settings = {
      :address  =&gt; "smtp.mydomain.com",
      :port  =&gt; 25,
      :domain  =&gt; "mydomain.com",
      :user_name  =&gt; "admin@mydomain.com",
      :password  =&gt; "CorrectPassword",
      :authentication  =&gt; :plain,
      :enable_starttls_auto =&gt; true,
      :openssl_verify_mode =&gt; 'none'
    }
  
    config.action_mailer.default_url_options = {:host =&gt; "mydomain.com"}
  </code></pre>
  
  <p>The same works when I use my gmail account settings. I got my domain from bigrock.com and all MX Records are verified. I am able to send emails manually (by logging in webmail.mydomain.com). This issue has delayed the release of my site by quite a few days. Please Help!</p>