First Class Mail
First Class Mail is material wholly or partially handwritten (including carbons), postcards, completed forms, statements, invoices, and typewritten or computer processed correspondence. This is what most people have in mind when they mail something through the United States Postal Service. All mail-able matter may be sent as First Class Mail with the exception of certain items shown in the Domestic Mail Manual C010.9.0. In addition, the following items may be mailed only as First Class or Express Mail: matter that is written or typewritten, matter that is closed against postal inspection, matter having the character of actual and personal correspondence, bills and statements of account.
First Class Mail receives expeditious handling and transportation in an effort to achieve the following service objectives: overnight delivery between the point of mailing and the locally designated cities and sectional centers, second day delivery for locally designated states, third day delivery for the remainder of the United States. The USPS does not guarantee the delivery of First Class Mail.