title: Using environment variable for 'recipients:' in Jenkins Pipeline Mailer
body: <p>I have a list of email ids in a Jenkins environment variable(emailsdl) and trying to use this for <code>recipients:</code> in Jenkins Pipeline Mailer as below:</p>
  
  <pre><code>mail (to: 'Mailer', recipients: '${env.emailsdl}',
   subject: "Job '${env.JOB_NAME}' (${env.BUILD_NUMBER}) is waiting for input",
   body: "Please go to ${env.BUILD_URL}.")
  </code></pre>
  
  <p>With the above code I am not receiving email and receiving an error: </p>
  
  <blockquote>
    <p>Email not sent. No recipients of any kind specified ('to', 'cc', 'bcc').</p>
  </blockquote>
  
  <p>But when I replace <code>${env.emailsdl}</code> with real email(xyxyx@foo.com) then it does trigger an email. I even tried  <code>env['emailsdl']</code> and it didn't work. </p>
  
  <p>Is there a way I can pass environment variable for recipients in this case?</p>