There are many companies in business to help you mail. They include:
Presort Bureaus and Letter Shops
Presort bureaus and letter shops specialize in preparing bulk mailings for customers. Some of these businesses will do it all for you - everything from creating your mailpiece through dropping it off at the Post Office. You can find these businesses by doing a web search or looking in the yellow pages under "letter shops, " "mailing services, " or "printing." Use Business Mail 101 to learn what’s involved in preparing a bulk mailing, then check with a few presort bureaus or letter shops to see what services they offer. Compare your costs and efforts in preparing the mailing yourself to the costs of paying a vendor to do some or all of the work for you.
Many companies sell "presort software, " which is special computer software that presorts your addresses, figures out how many mailpieces will qualify for which postage prices, and prints out a completed postage statement. Presort software can cost anywhere from about $100 (for simple packages) to thousands of dollars (for very sophisticated software). You can find presort software at your local office supply store. Look for software that is "PAVE certified" - that means that the software has been tested and approved by the Postal Service.