My business Quick Tip newsletter (www.successis.co.nz) is one of the longest running in New Zealand and Australia. I started it in 1999, and I'm proud to say I rarely get unsubscribes.
Mail Delivery Errors from people leaving jobs - yes, but few pure unsubscribes from purely not wanting it.
I believe there are the five vital components of a successful marketing email.
1. Database
2. Content
3. Technical setup/design
4. Distribution
5. Response management
Each component has significant bearing on how well received (or sadly - received at all) your email newsletter will be; and if action is required, it is taken by your recipient. Let me share my top three database tips with you.