Express Plus uses Bayesian Mail Filtering to quickly learn what messages you consider to be good and bad and start blocking the bad immediately! Bayesian filtering is great for getting that annoying SPAM out of your inbox and more effective than the mail filters you might create by hand that spammers always seem to find away around!
Mail-merge creates personalized individual messages rather than simply sending the traditional Dear Friend letter. Your business has done it for years on paper letters so why shouldn't you be able to do it with your email program, too?
Use mail groups for sending messages to focus on just the group of names you want to send this message to rather than fumbling through the entire address book.