Solo Ad Blast to 500,000 Readers! (that's half a Million emails sent! .. all SPAM-FREE!) This is the guts of our service. Your solo ad sent to our entire database of over 500,000+ opt-in prospects! This is our Mailbox Money Solo List. (20+ Years to build) 100% opt-in. Your solo ad is specifically designed (in full html & text) to pull visitors to your web site.