There are many ways to receive proof that your bulk mailing was mailed. The easiest way it ask your mail house for a postal receipt. When bulk mail is delivered to the post office the postal clerk will examine the piece make sure it meets the postal standards and weight verify the delivery to ensure that the quantity matches that in the postal statement. They will then issue a mailing transaction receipt acknowledging that the mail has been delivered and is now in the hands of the USPS. The postage statement will also detail the postage paid. Many post offices are now sending these receipts electronically and they should be accessible for mail houses to distribute if there is a discrepancy.
Bulk direct mail can also be tracked. The mail house can add information into the barcode of the mail piece which will allow the USPS to track the piece as it moves through the mail stream. Your mail house can then provide a report indicating where in the mail stream the pieces are. Tracking goes as far as the last scan from the last post office prior to delivery, but does not track when the piece is actually delivered to the recipient’s mailbox. Furthermore, tracking is not 100% accurate as some pieces are not scanned and depending on where the mail is going some USPS post offices do not have the technology to track all types of mail.
In some cases the two aforementioned methods will not be available like for some first class, non-automation, comingled, or international mail. In these cases the best way to track whether the pieces have been delivered to the post office is to add a seed name into your data. A seed name is often times an address included in the data used for purpose of verifying that the mail has been sent. It is best practice to include seed names in all mailings, not just to verify mailing but also to get an idea of when recipients have received the mail.