title: extracting recurring patterns from a file
body: <p>I got a list with about 880 lines.
  A example line looks like this:</p>
  
  <blockquote>
    <p>attr1=sample,attr2=sample,attr3=sample,<strong>email=example@example.org</strong>;<strong>EMAIL=example@example.org</strong>attr3=sample,attr4=sample,attr5=sample,<strong>EMAIL=example@example.org</strong>,attr5=sample,attr6=sample,<strong>email=example@example.org</strong>...</p>
  </blockquote>
  
  <p>I'd like to extract only the email attributes and delete the rest. Does this work with sed?</p>
  
  <p>Thank you very much and kind regards!</p>