title: Run a string as an instruction to build an email
body: <p>I have a table in which I save an ID and a rule like:</p>
  
  <pre><code>|  ID  | Rule                                 |
  |------|--------------------------------------|
  |  1   | firstname[0]+'.'+lastname+'@'+domain |
  |  2   | firstname+'_'+lastname+'@'+domain    |
  |  3   | lastname[0]+firstname+'@'+domain     |
  </code></pre>
  
  <p>My problem is: How can I get and analyze/execute that rule in my code? Because the cell is taken as a string and I don't know how to apply that rule to my variables or my code.</p>
  
  <p>I was thinking about <code>String.Format</code>, but I don't know how to split a string taking just the first character with it.</p>
  
  <p>If you could give me an advice or any better way to do this, I'd appreciate that because I'm completely lost.</p>