title: Use Environment variable inside HTML body in Jenkins Pipeline
body: <p>I have a Jenkins Pipeline which sends email to the recipients using Jenkins email-ext plugin.
  In the emailext body, I have added HTML code to send the mail in a specific format. However, when I try to use the environment variable, it does not return the value of the variable.</p>
  <p>In my pipeline, I have set</p>
  <blockquote>
  <p>SERVICE_NAME = &quot;Service Variable&quot;</p>
  </blockquote>
  <pre><code>emailext body:
   ''' &lt;html&gt;
       &lt;body&gt;
      
      &lt;div style=&quot;padding-left: 30px; padding-bottom: 15px;&quot; color=&quot;blue&quot;&gt;
      &lt;font color=&quot;navy&quot; size=&quot;5&quot;&gt; &lt;b&gt; ${SERVICE_NAME} &lt;/b&gt; &lt;/font&gt; &lt;br&gt;
      &lt;b&gt; Build &lt;/b&gt; &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp; &lt;font color=&quot;blue&quot;&gt;# ${BUILD_NUMBER} &lt;/font&gt;&lt;br&gt;
      &lt;b&gt; Git Branch &lt;/b&gt; &amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp; &lt;font color=&quot;gray&quot;&gt; ${BRANCH_NAME} &lt;/font&gt; &lt;br&gt;
      &lt;b&gt; Status &lt;/b&gt; &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp; &lt;font color=&quot;red&quot;&gt; ${BUILD_STATUS} &lt;/font&gt;&lt;br&gt;
      &lt;b&gt; Cause &lt;/b&gt; &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp; &lt;font color=&quot;gray&quot;&gt; ${BUILD_CAUSE} &lt;/font&gt;
      &lt;/div&gt;
      &lt;div style=&quot;padding-left: 30px; padding-bottom: 15px;&quot;&gt;
      ${CHANGES, showPaths=true, format=&quot;&lt;div&gt;&lt;b&gt;Author&lt;/b&gt; &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp; &lt;b&gt; %a &lt;/b&gt;&lt;br&gt;&lt;b&gt;Commit-Id&lt;/b&gt; &amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp;  %r &lt;br&gt;  &lt;/div&gt;&lt;div style=\\&quot;padding-left:30px;\\&quot;&gt; &lt;b&gt; Message &lt;/b&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; : &amp;nbsp;&amp;nbsp;&amp;nbsp; &amp;#8220;&lt;em&gt;%m&lt;/em&gt;&amp;#8221;&lt;/div&gt;&quot;, pathFormat=&quot;&lt;/div&gt;&lt;div style=\\&quot;padding-left:30px;\\&quot;&gt;%p&quot;}
      &lt;/div&gt;
      &lt;/body&gt;
      &lt;/html&gt;''' ,       
                          mimeType: 'text/html',
                          subject: &quot;Some subject &quot;,
                          to: 'mail.com'
                  
  </code></pre>
  <p>OUTPUT:-
  ${SERVICE_NAME}</p>
  <p>Instead it should return &quot;Service Variable&quot; in the mail.</p>
  <p>Any help regarding this please?
  Thanks!</p>