The U.S. Postal Service establishes and publishes in the Domestic Mail Manual (DMM) an extensive list of requirements with which business mailings must comply. These requirements determine (among other things) acceptable envelope sizes, position and sequence of address lines, graphic restrictions, and mandatory “clear zones”.

The DMM is available in two formats: paper and electronic.
The electronic version of the DMM is available in two formats: on the Internet and on an interactive CD-ROM. The internet address is http://pe.usps.gov, where the DMM is updated monthly.

While it is impossible to list all the requirements, here are a few which should prove helpful. Consult with your local Postmaster where envelopes will be mailed from, on any additional questions you may have.