Not just a violation of my MLS rules, I add them to my block list, report them as spam to my email provider. I look at the MLS several times a day, I could care less about:
1-You offering a bonus-my buyers make the decision on which house they want, I don't "push" houses because of bonuses.
2-Price reductions and New listings have their own category on front page of MLS that I check several times daily in addition to me searching for my clients, and auto searches-no need to spam me!
3-Agent Open House- thank you, if able I will come, not to eat or enter drawing for prizes but to see the property for my buyers.

Not really if you ask me. When I first received those, I'd look at it, but now they go to my spam email.

If I have a client for specific properties, I am like a hawk all the time, watching for those properties to show up, I don't need other people's email blast to remind me.

I do have property sites which allows consumers to see the property more closely (MLS only allows for so many tiny little pictures), and often attract them to come and see the house during open house or ask their Realtors to show them the home. Not from email blasts though (I also received a couple of 'hate' mails when I tried it a few times before).

It might work for a very unique property.

Sylvia