Email marketing is pretty much spam
This is one of those things that I shouldn't have to write but apparently I do: anything that is called 'email marketing' is pretty much always spam, and everyone involved in it either knows this or is actively hiding their head in the sand. Theoretical good intentions in this do not matter, because there are simply too many pressures pushing the other way. There are too many reasons for salespeople to lie about whether their leads have consented to email, too many reasons for the marketing department to be optimistic, too many reasons for management to look the other way no matter what, and so on.
(One of my theories is that it has not sunk in to any layer of sales and management that email is drastically different than physical mail, not just technically but socially. Socially, I think that email is in at least some ways much more like a phone call than like postal mail. Not that this would stop some marketing organizations, of course.)
This goes at least double if you are a company that is selling 'email marketing' services to other people. Even if you desire to be entirely legitimate, it is extraordinarily difficult to avoid being exploited by the various forms of spammers (which include optimistic and willfully blind marketing departments). I'll go so far as to say that it's basically impossible to do so; the precautions necessary to not spam are uneconomic and make you completely unattractive to even legitimate companies.
(Alleged good intentions do not matter at all, of course. No one believes them, because the spammers have long since poisoned that well.)