Last week, Yahoo confirmed that they are altering their email filtering algorithm to place a higher weight on reader engagement. Gmail and Hotmail implemented similar changes recently, too. This means that if your readers aren't opening your messages or clicking on your links, your emails could be routed out of the inbox and into the bulk mail folder. Yahoo delivery is declining across the board. So, even when your email service provider is whitelisted (like MailerMailer), if your readers aren't responding to your messages, Yahoo's inbox is taking notice. They are looking at whether your email subscribers delete your messages without opening them. If they see this trend, zap - off you go!