The use of bulk mail services for direct mail campaigns (minimum 200+ pieces for standard class mail and 500+ pieces for first class mail) can yield big cost savings; as much as 17 cents per piece compared to a regular first class stamp. But there is truth in the adage that "you get what you pay for" so its important to know the difference between these two classes.
The USPS recently added an extra day to estimated first class delivery times, but you can still expect mail to be delivered between 2-7 days anywhere in the U.S. other than during peak times (holidays, tax season, etc.). In contrast, standard mail takes up to 21 days to get delivered under the same circumstances. That's a big difference if timing matters for your campaign.
First class mail is automatically forwarded for 12 months if your mail recipient has notified the Postal Service of their new address. After 12 months, the mail will be returned to you, as will other non-deliverable mail, such as those that are illegibly addressed. Standard mail is not returned and won’t even be delivered if the recipient has moved, unless you include an exceptional address (or current resident, valued neighbor, etc.) to your mailing. So if your list is fresh and updated frequently, this might not make a difference to you. But if you have legacy records, your mailing may end up nowhere.
Clearly, advance planning is required if you want to take advantage of standard mail postage costs, and it does save money. However, the easiest way to minimize postage costs and improve mail accuracy is to ensure your list is up to date. The Postal Service requires all mailing lists to be run through CASS (Coding Accuracy Support System) software, but it isn’t perfect and it doesn’t guarantee your mail is delivered to the right person. An accurate list does. It’s a good habit to run your mail lists through a NCOA (National Change of Address) system once a year, which sends you back the new addresses of people who have moved in the last 12 months. If you haven't done this in the last year, you can order a data append that sends back address updates older than 12 months.
Marketing firms that offer direct mail services should also offer these types of data management services. So it’s worth investing some time and effort in advance for your direct mail projects. That way you can lower your postage costs and improve delivery accuracy, generating improved ROI.