An increasing number of races are shipping items to their participants before the race (or after!). Some races charge a shipping charge, and some bundle it into their pricing. However, if items are returned, that can create frustration for the participant and a lot of overhead for race directors. If you have ever bought something on Amazon (who hasn’t), you will notice they validate your address if it is new. This is done by checking with the US Postal Service database in real time.
There is a difference between validation and suggestions. This is handled by USPS.
Validation will not let anyone continue with an address that is not accepted by USPS.
May all your packages arrive on time!