Yes!
Once you have the outlook add-in installed your sales person can compose an email via outlook as always, add an attachemtn and click "Send & Track".
The attachement will not be tracked in any way shape or form, there will be no record of it in Marketo, but it will go through along with the email.
If you want to know if the recipient has viewed the attachement, the only way is to host the attachment in Images & Files (or elsewhere) and add a link to the file to the email as opposed to attaching directly.
I hope this helps!
Reza.