I have an e-mailing list of over 6000 people for sale to those interested. Around 500 brokers, 500 landlords, and over 5,000 clients targeted over the last 10 years.
Completely legal as these people didn't sign an opt-in form. I also never signed an NDA or Non-compete clause. It's just a list of perfect leads.

A large portion of our business has been done with word of mouth and this list. I'm selling it to five offices and that's it. Feel free to message if interested. I'll send a copy of the list with only names/companies. I'll leave out their exact email addresses until I receive half payment. These are excel sheets that can be imported into MailChimp or CampaignBreeze. You can then formulate your campaign email and send to them all simultaneously.
[{"id": "ib3pq87", "text": "Selling people is definitely illegal. How did you acquire said professionals to sell? Where did you keep them for ten years? I have many questions.", "replies": [{"id": "ib3r58x", "text": "This probably answers some of them\u2026.\n\nhttps://www.reddit.com/r/antiwork/comments/v2yxj5/i_quit_a_wellpaying_job_today/?utm_source=share&amp;utm_medium=ios_app&amp;utm_name=iossmf", "replies": [], "depth": 2}], "depth": 1}]