Adding my 2 cents worth!
Listening (reading!) how everyone feels about their overloaded Inbox, I would say the secret to email marketing, is hitting the right note and getting people's attention - the very first time!
For me that would be a mixture of witty comments, free information (sharing something helpful with no added sales pitch) and imagery/branding.
Maybe try your idea on a friendly audience (your own free email contacts) and get feedback before buying a targetted list?
D