<p>For many of the schools I'm applying to through the CommonApp, 2 letters of recommendation (or "Teacher Evaluations" as they call it) are required. One of my teachers has already submitted his online, but the other teacher I asked refuses to do it online. So is it acceptable to send one in online and the other in through the mail?</p>
<p>I am pretty sure you can do that. Whether the forms are submitted by paper or online depends on the official, not by your application.</p>