Ideally, you want to have each customer’s correctly spelt name and up-to-date address, phone number and email address (unintentional mistypes are very common).
If you receive an undelivered email, for example, call them to check what address to use.
Having several ways to reach a client is great for retention since you can contact them appropriately for the situation. For example you might call them to discuss coverage and claims, post them a Christmas card, email them with a cross-sell offer, or text them to see if they need anything after a sudden and destructive storm.
Remember that for commercial accounts there is always a key decision maker. So ideally try to get their particular contact details - and send communications directly to them.
If a customer or their partner gets divorced or passes away, remember to remove the person’s name from your management system, and from anywhere else that you hold customer information.