SSL mandatory or not FOR OE PayPal 3.1.1 ?

Hello

I'm reading the OE PayPal 3.1.1 module manual System requirements: "In addition, the PayPal module only works if the OXID eShop was configured for SSL mode.".

I have read somewhere (really can't find the source anymore) that SSL is only needed when PayPal is configured for Express Checkout.

So no need for SSL mode when not using Express Checkout option?
Can anyone confirm this from experience (Oxid CE 4.8.4) ?

Thanks in advance