Why would a school think it's a good idea to put student email addresses in a publicly available student directory??

I'm an online teacher for a private school. Every year, we produce a student directory which contains student names, parents' names, addresses, and phone numbers. In the past, we have only done this in a paper version, but a while back we added a digital version. <br><br>For reasons I can't understand, they decided to include student email addresses in those directories. I've shared them with parents each year, as instructed. <br><br>Are there legitimate reasons to do this? I'm really confused.