A piece of malicious code delivered via an executable attachment in email or over a computer network and which spreads to other computers by automatically sending itself to every email address on a recipient’s contact list or address book. See virus.

3 Quick And Easy Ways To Build A Profitable Opt-In List
You finally realize that you need a good opt-in list. After reading countless articles and sought expert advices and have read many success stories of people creating a small fortune with opt-in lists you finally decide to have one of your own.