[hijack]
DISagree! 
My coworkers and I use this at least a few times a day. It’s extremely (and frequently) useful. Especially when 2 or 3 of us (plus the clients) are working on the same project and you are simply communicating back and forth about that particular project or project phase.
And it’s quick and easy for the lazy human.
Given that both the instructor and the state agency are running businesses, and you are a customer, I’d say
[ul]
[li] the state agency was in violation of CAN SPAM laws. You had no existing business relationship with them, nor did they get your permission to market to you. Presumably the instructor never said anything about making your info available to third parties as a condition for subscribing to her list.[/li][li] the instructor, at best, violated a whole bunch of industry best-practices rules. I’m not sure where giving away an email list sits with the law (as opposed to selling a list), but it’s a definite no-no with regards to how legitimate businesses conduct their email marketing. So is letting the entire mailing list have your email address.[/ul][/li]
Basically, customers have every right to expect that a business won’t use their contact information for any other purpose than what the customer agreed to. Legit businesses respect this (and, ideally, codify it into a privacy policy). Shitty businesses don’t. So yes, she was unprofessional to give your info away, unprofessional in her tone of reply, and unprofessional not to take her lumps and apologize profusely when you called her on her unprofessionalism. If she’s running a business, she needs to act like it. If she doesn’t want to, her customers will likely go elsewhere.