Because the companies know from experience that once they have a customer, he will normally buy something else. That buyer of the new software package will probably buy the upgrade to it later on. Companies talk in terms of the 'lifetime value' of a customer. This can be many times the value of the original sale. More people have gone bust in the 'mail order business' trying to make money from a single product than in any other way.
Email marketing runs along a similar vein and the guidelines for success remain the same.
Lesley Anne Lowe is publisher of Advance Consultancy News, a weekly newsletter devoted to online marketing techniques, maximizing online profits and developing 'killer' advertising strategies. Copyright 1996-2001 Horizons Unlimited Group . All Rights Reserved.