title: Using .forward to preprocess incoming email?
body: <p>I have no previous experience with procmail.  I have written a filter to repair broken headers in certain emails that I receive.  I need to set up my .forward file to run the repair filter without breaking the existing email processing.</p>
  
  <p>Let's say that the current .forward file is</p>
  
  <pre><code>|IFS=' ';exec /usr/local/bin/procmail #username
  </code></pre>
  
  <p>Would I add another line above it in the file, or would I interpose the filter in the existing line like</p>
  
  <pre><code>...exec filter | /usr/local/bin/procmail #username
  </code></pre>
  
  <p>EDIT: I don't think that the single-line process would work, because the file in the .maildir/cur would still be bad.  I need to modify that file, preferably as it lands in ./cur.</p>