Standard Three-Line Block

• According to the U.S. Postal Service, an address is considered minimally complete when it contains a ZIP code plus the 4 digit extension, city and state, street address, and a recipient (either a specific person or business name). An address is considered standardized when it is fully spelled out (no abbreviations). The three lines should be left-justified and all capital letters. For example:
  
  JANE SMITH
  101 MAIN STREET
  RALEIGH, NC 27612
  
  Capital letters are preferred by the postal system (and best for automated machines) but they are not required. Letters with regular capitalization will still be routed to their recipients.
  
  

Attention Line

• When you send a letter to a specific recipient at a business, the envelope should be addressed to her attention above the name of the company. For example:
  
  ATTN JANE SMITH
  CAT SERVICES
  101 MAIN STREET
  RALEIGH, NC 27612
  
  An attention line is not required to send mail (nor is a company name), but it helps get the letter to the correct recipient, especially in large companies where mail is sorted by department or personnel.
  
  

Title Etiquette

• U.S. postal standards state that the courtesy titles Mr., Ms., Mrs., etc., are not required when addressing an envelope. If you wish to use the title, it is best to go with Mr. Smith or Ms. Smith (not Mrs.). Recipients who have degrees or titles may be addressed as so: Jane Smith, R.N.; Dr. Jane Smith; Jane Smith, Esq. (do not spell out Esquire). When using a professional title, eliminate the courtesy title: Jane Smith, Esq, not Ms. Jane Smith, Esq. Eliminating the courtesy title will help when you are unsure of a person's gender and do not want to make an assumption or a mistake.
  
  

Last line

• The last line of the address contains some of the most important information: city, state, ZIP code, and 4-digit extension. This line should consist of the city's name (not abbreviated), one space, the two-letter abbreviation for the state, two spaces, the 5-digit ZIP code, a hyphen, and then the 4-digit extension. For example:
  
  RALEIGH NC 27612-5670
  
  

Readability

• Offices using automated postal machines or printing large quantities of envelopes must take care that their envelopes comply with readability regulations. Readability guidelines for business mailing suggest up to five lines for an address:
  
  1. An optional line of non-address data (subscriber number, for example).
  2. The person to whose attention the letter is addressed (optional if the letter is a general mailing to a company).
  3. The name of the business to whose attention the letter is addressed.
  4. Delivery address (street/road).
  5. City, state, and ZIP code plus 4-digit extension.
  
  Example:
  
  083712247
  MS JANE SMITH
  CAT SERVICES
  101 MAIN STREET
  RALEIGH NC 27612-5670
  
  Machines processing mail perform best with dark ink on a light surface. Each character should be separate, not touching or smeared. If the business will be using a bar code, the address area should be printed high enough on the envelope so that the bar code will not overprint.