You can try Spread - email marketing software & service, they have good relationship with major ISPs like hotmail, yahoo, aol etc.

Basically, your email server needs to be whitelisted and/or have a proper sender policy framework in place. It will be easier to outsource your newsletter service to an email provider, like Mail Chimp or Bronto, etc.

Personally, I use AuthSMTP and integrate their SMTP service into my applications.

It is virtually impossible to guarantee that none of your emails will ever land in junk mail. This is because various users have different spam filters and settings on their PC's or corporate servers. A bank's employees for example, will typically have extremely strict spam filters on their email servers, which means that you'll have a hard time getting through.

Generally speaking though, Tzm's answer is right on the money: Your chances of NOT landing in the junk mail will increase tremendously by using email sending services, which are whitelisted and recognized with various anti-spam organisations. The problem with using your own mail servers is that they will very often just be considered "semi-legit" by the large spam filters.

We have been recommending Constant Contact to our clients for awhile now and everyone loves it. It is very easy to use and very powerful.