I would Google your intended major and see what colleges come up and start there. If you are undeclared, then maybe search colleges and universities in your state or a state you would like to attend. Most respectable colleges have a link to add yourself to their mailing address.
I do not recommend mass mailings like your question suggests, you will get a ton of junk mail from every tom, **** & harry that tries to sell stuff to prospective college student that will be hard to get off their mailing lists. Trust me on this.