How can I confirm that an address is valid?
If you have an address list that you want to make sure has valid and current address information, the best way to clean up the list and validate the addresses would be to use our NCOA and CASS address clean-up tools. For more information on that, you can visit our other help topic "How do I clean up my address list?".
Also, when you load an address list into your LetterStream.com account and build a job, our system will flag all addresses that it registers as an international or bad address. These addresses will be highlighted in pink, so you can clearly see the addresses in question and then decide if they are indeed international addresses, or if the address was uploaded incorrectly.
From there, you can update any bad addresses if needed. But if you decide to run your address list through our NCOA or CASS tools, that will discern bad addresses as well.
Also, see our post "What information do I need to include in a valid recipient address" to learn what information should be included in an address.