There are requirements for a commercial electronic mail message whose purpose is to promote a commercial product or service. It doesn't sound like you're in that area. But I would allow some type of opt-out so that you don't pester a customer who doesn't want these messages. If you have an opt-out list now, remove the messages for them.
If it could be an ad under these rules, you have to include an clear indication that this is an ad, your physical address and the opt-out.
My opinions are not necessarily my employers.
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell