There are more than 10 categories in my site, users can register more than one category. My php script prepare contents of each category, according to user preference my script merge those contents for each user. so every user can get what category they want.

Problem is I want to send 340+ mails per hour and dreamhost dont allow.

What do you suggest?

I think to a service like mailchimp but I couldnt find that scenario, do they support category & content etc. Can I use smtp in dreamhost?