The important thing is to target your email subscribers. If you have a niche or authority site and make a relevant offer to your visitors to sign up then you will get a targeted audience who are guaranteed to be interested in your emails, they wouldn't have signed up if they weren't at least a bit interested.

If you are buying a list or obtaining it in another way that gets you just a list, there is no way you know how interested they will be in your emails. Its better to have 100 on your list that buy than 10,000 on a list that don't even open your emails.

I've talked to AWeber about buying mailing lists. The thing they say is if they get too many member cancellations too fast. It raises red flags and they may ban you. Also, there are maybe a hundred spam blocking sites. If you get listed it's difficult to get delisted and they'll block your site to their subscribers. Best to check the validity of your email addresses and and add them slowly. Some sites I know have been spam listed and had to change hosting companies and domains in order to function. Be careful!

Be careful if you are recommnding this and you then recieve income from it as an affiliate OK

Thats really useful, thanks for posting....