There are two ways to look at the cost of spam.
Costs me nothing to ask and a few will say yes, so its worth it.
Every conversation is a journey. Each interaction builds on the prior
interaction. Every time you touch someone in the outside world it costs
you something and it costs them something.
How you answer the question will effect everything.
And while we're talking about spam…if you didn't send out that "e-newsletter" of yours, how many people would miss it enough to call you and ask where it was? If people don't miss it when its gone, I'd argue you don't really have a true permission asset. I don't care if your privacy statement gave you permission to send me email. A true fan would be mad if they found out they'd been left out of a timely and relevant communication.
What would it take for people to actually look forward to seeing your email in their inbox?