SSL Certificate with Paypal IPN

I have just added a paypal button for a client site to take deposit and balance payments. No information is taken on the site - that’s all handled by payp[al.

However, I haver read that if your Paypal plug in hooks into the Paypal IPN you need to have a secure site. Anyone knowledgable on this subject? I think a Yuzool Paypal stack links to the IPN but do the others?