Naviance and Teacher Recommendations

My school uses Naviance, but I’m confused about the process of sending letters of recommendations. Are teachers absolutely required to upload the recommendations electronically with Naviance? Can they send them by mail? If one teacher uploads the reference online, do the remaining teachers have to send them in the same fashion?

:-?

They can send them by mail but colleges prefer for the process to be expedited by having the recs sent online. Teachers can send the recs in different way so it doesn’t matter. If one uploads online, the remaining can send it whatever way they choose/are most comfortable with.