Best Newsletter Plugin with several mailing lists?

Hi there,

I’m building a website where several flats are for rent.
Users should be able to enter their email adress for each flat individually.
The admin should then be able to send emails to either everybody (= all flats) or only people that registered for one certain flat.

Best newsletter plugin to make this happen?
I was thinking about PHPList but maybe there are lighter solutions.

What I don’t need: some widget solution. I need to be able to insert a registration form on pages.
Actually I don’t even need HTML mails.

I already spent some time looking for plugins like that, didn’t find the perfect one.

Thanks for your help!