Most people tend to send most mail first class. Sure U.S. Postal shipping also sends things priority mail and overnight delivery, but what you may not know is that they also ship mail via other classes. Shipping mail via anything other than first class means that whatever you send will take longer to reach its destination, based on class. So, why would you select anything other than first class shipping? To get a reasonable answer to that question, you must first know and understand more about other shipping classes.
Second- Through Eleventh Class Mail
Right about now, you are probably thinking, "Whoa! Eleventh class mail?" Yep, that is as low as you can go on the mail class totem pole. However, almost no one ever requests to send mail under that class, or any class past fourth class. These services remain offered by the post office, with the acknowledgement that they are not likely to be requested, but exist all the same.
As is the case, each class of mail delivers far more slowly than the two- to three-day delivery of first class mail. For example, people sending bulk mailings via fourth class* mail will need to mail every piece about five to seven days before they want recipients to receive it. (Most people need and want faster delivery on important mail.)
Reasons for Shipping Other Than First Class
There are actually some good reasons for choosing to ship mail under other, slower classes. For one, you want to save a lot of money on postage. Whether you ship fifty pieces of mail, or fifty-thousand pieces of mail, it helps to ship it at a lesser class because the postage costs far less. There are a few caveats, such as having to sort your mail yourself, and making sure it is in perfect alphabetical order or numerical order by street. Still, paying a fraction of the first class postage costs is worth it to some people.
Two, you may be trying to time the arrival of the mail just right. Maybe you have been tasked with mailing store flyers, but the boss says that the flyers cannot arrive before a certain date. Then you would mail the flyers according to the date on the flyers and the expected speed of delivery. Thankfully, a postal worker can help you figure out exactly what class of mail and postage you need to use.