CBP recently issued a cargo notice reminding importers that, if their addresses are wrong in the CBP system and mail is returned, their bonds will be rendered insufficient, i.e., canceled.
Each time mail is returned, CBP works to acquire the correct address, but if the agency is unsuccessful, it has an easy way to get the importer's attention. It simply cancels his bond. If it turns out CBP is wrong, the importer has recourse; but the really interesting question is how often does CBP first check its own address database? There is still a myriad of mail being addressed by CBP to importers at addresses that were vacated long ago and superseded by updated 5106 filings, but the new addresses are not being used. Make sure that your address is current and accurate in the CBP system by checking with your customs broker. If it is not, you should immediately file a CBP From 5106 and update the data.