Yeah, you'd be violating the contract under those terms.
If he authorized you thinking you're a regular Joe who's expecting personal emails from you and you start sending him weekly newsletter emails promoting your toy site - you're violating the contract.
If he KNOWS you run a toy site and agree's to receive your weekly newsletter about toys and you decide to add his email to your porn email database and start sending him porn newsletters too - you're violating the contract - it's not they type of newsletter he signed up for and agreed to receive from you.
If you want to send the guy "other" newsletters and he's already accepting one from you, send him another and simply say:
I have other types of newsletters I send out and if you'd like to get one on "___", send me an email at
[email protected] and Spam Arrest will automatically add me to your acceptance list.