In the code listings that accompany a couple of my Outlook VBA on Demand columns, you might have noticed the On Error Resume Next statement. Until now, I haven't explained the statement's purpose, except that it lets Outlook continue running code after an error occurs. Any good program that goes beyond the sample stage into production use has some mechanism for dealing with errors. In this installment, I explain more about error handling—specifically, when you need it and how to implement it.

You...