Now a days people seem to be constantly changing their contact details. People get new phone nos, open new email accounts, change job or move house. By assuming old data is up to date you may well be missing out on contacting loyal, interested customers who have changed their contact details. Equally you might be creating negative perceptions of your company by contacting people who do not want to be contacted any more. In essence, cleaning your data will reduce your campaign costs, improve your profitability, maximise customer relationships and avoid negative implications of getting it wrong.