My original thought for this posting was to list and explain them all, as I've done for other stages within the customer acquisition lifecycle. But after thinking through this subject in more depth, I came to the conclusion that there really is only one main digital retention tool ..... email.
Well, if you think about it, how do you typically get contacted by an online retailer to suggest another product from their new range you might like? How do you find out your favourite band is touring again (if you're not already browsing their website, most likely during work hours)?
Sure, you have other methods.... (and I need to ponder subsequently the value of social networks such as Facebook for creating customer loyalty) however in my mind the principle digital tool for customer retention is email.
Does anyone disagree?