Best email program for sending marketing materials to large groups.?

I'm setting up several large email groups (100 + contacts per)that I will need to email marketing materials to on a regular basis. Obviously, Outlook is not the best program for this. What is the best program to perform this function that won't give me positive points on Spam detecting filters. BTW, I am not a spammer, this will be going to our customers and prospects that are expecting the email.

Best email program for sending marketing materials to large groups.?
If you don't want to pay monthly expensive fee, you can check this site:


http://www.scripts4webmasters.com/





If you are a non-techie and complete newbie, go with this with monthly fee:


http://www.aweber.com/