All the casinos I sent a mailer for gave away bonuses. No freebies as far as I remember – but I could be wrong.
All got the exact same mailing list. Same players. I bought the list and am the only person mailing to it.
All had exactly the same time distance between mailings.
The number of depositing players per mailing varied from 20 (playtech) to one (RTG)
The money I earned from each mailer in the first week following that mailing varied from $1400 (micro) to $3 (RTG)
The RTG didn’t even get a decent number of clicks – a third of what most of the others got. If there were freebie players – they didn’t even bother to click.