Would it be possible to get a custom filter for the newsletter module that would allow me to send a newsletter only to users that i have never sent a newsletter to before. So that i can specifically target new users?
You can do that now in a variety of ways.
* put all new users in their own quota, move to different quota once logged in, sent emails to that quota.
* use the "have never opened a newsletter" filter
* use a custom filter of: user_last_login = 0