title: grep -wF "example1@domain1.org" filename.txt and special characters
body: <p>Inside filename.txt I've:</p>
  
  <pre><code>example1@domain1.org example1@domain1.org
  example2@domain1.org example2@domain1.org
  example3@domain1.org newexample3@domain1.org
  example4@domain1.org oldexample4@domain1.org
  example5@domain1.org otherexample5@domain1.org
  </code></pre>
  
  <p>I need search inside it the exact match, the result of:</p>
  
  <pre><code>grep -wF "example1@domain1.org" filename.txt
  </code></pre>
  
  <p>it's correct.</p>
  
  <p>My problem is that grep show me correct result also if I do:</p>
  
  <pre><code>grep -wF "example1" filename.txt
  </code></pre>
  
  <p>maybe, is the @ (special characters) problem.</p>
  
  <pre><code>-w, --word-regexp
  -F, --fixed-strings
  </code></pre>