title: Mimekit installing certificates upon verify
body: <p>I am using <code>MimeKit</code> to verify that an SMIME multipart signed message is signed by a specific entity. I have the public certificate for this entity. When calling <code>Verify(context)</code> on the <code>MultipartSigned</code> object, the certificate is being imported into the servers certificate list. What I want is that this errors if the certificate is not found. otherwise if a malicious user signs a file it would pass through, and what's worse I would end up with his certificate installed.</p>
  
  <p>Is my reasoning flawed here?</p>
  
  <p>This is the code I'm using.</p>
  
  <pre><code>var signed =(MultipartSigned)MimeEntity.Load(ParserOptions.Default,@"C:\mysignedfile.txt");
  
  using (var context = new WindowsSecureMimeContext(StoreLocation.LocalMachine))
  {
      foreach (var signature in signed.Verify(context))// This install the certificate!
      {
          try
          {
              bool valid = signature.Verify();
          }
          catch (DigitalSignatureVerifyException)
          {
              throw;
              // There was an error verifying the signature.
          }                    
      }
  }
  </code></pre>