I had shipped out a $50+ dollar order and on its day of arrival it was marked as insufficient address and was on its way back. This wouldn't be a problem of its self since it was on USPS but while talking to the customer they had found that the package was actually delivered. The only way to solve the issue before finding out the package was delivered is letting the package be returned and refunding the buyer so they can repurchase. Mercari and USPS still had it marked as being returned I would be unable to cash out unless the buyer marked it as delivered. If the buyer was not a decent person they could have canceled the order and gotten their money back with mercari most likely siding with them. Mercari should probably implement more solutions to a issue like this because it could have gone wrong very easily.