Mailing list how to manage

[Mark Turner]

Hello,
I am new to IM and JVpro. Everybody is saying that mailing lists are key to IM. My question is, how do you manage mailing lists when you market so many products? Whether you are selling IM or solar DIY, do you ever put all your lists together for a mailing or do you always just do focused mailings from lists that match the product? How often do you contact people off the list?
Thank you,
Mark