Below are two tips that I found on another forum that will help your emails stay out of the spam box.  For everyone that does email marketing, this is a post for you! (Note - GettingMoreVisitors.com does not support spamming.  Most of the time, even non spam messages get sent to spam boxes.  Here is a way to get around that!)

Tip:1

First you will need to find a provider who will sell you premade yahoo accounts. Usually the price is $20 per 1k or hire a team out of India who will create accounts for you. Premade accounts are called your seeds. Now if i were mailing a list of 10k yahoo emails I would purchase 20k seeds, your new email list will now be 30k emails. Now when you send your Advertisement 70% of the List will not Complain Nor Bounce and therefore your Spam Complaint and Bounce Ratio will drop tremendously.

Tip: 2

2 way communication between your seeds and Mailing Ips. Once you have purchased your 20k seeds find a coder on Elance.com or Rentacoder.com that Will make a Yahoo Bot, basically the Bot will take the Username & Password login to yahoo.com and send Mail back to your own domains that you will be sending from. This is a Quick and Easy way to Establish Ip reputation.

First Establish your Ip Reputation with yahoo.. Send Mail to your Mailing Ips so you don’t look like a spammer, then seed your accounts so your Bounce and Complaint Ratio are low. Enjoy the 2 to 3 weeks of Yahoo Inbox.

This best part is it can be applied to all the Big Domains!!!