Address Placement
New address placement standards apply to all Periodicals, Standard Mail, and Package Services flats mailed at presort, carrier route, and automation prices (optional for First-Class Mail). The delivery address must be in the top half of the mailpiece.

The "top" is:

• Either of the shorter edges on enveloped or polywrapped pieces.
• The upper edge when the spine or final folded edge is placed on the right-hand side of an unenclosed piece.
• Either of the shorter edges on saturation Periodicals and Standard Mail pieces, without regard to the spine or final fold.

The address must be entirely within the top half, with two exceptions: On a loose enclosure polywrapped with a host piece, at least the first half-inch of each address line must remain within the top half throughout processing and delivery. On a digest-size flat, a vertical address may cross the midpoint if it begins or ends within 1 inch of the top edge.

Address Characteristics
New address characteristics standards apply to all flats mailed at presort, carrier route, and automation prices.

Minimum Size

• All presorted and carrier route flats must be addressed using at least 8-point type (each letter or figure must be at least 0.080 inch high).
• Flats using an 11-digit POSTNET or an Intelligent Mail barcode may use 6-point type if the address is printed in all capital letters (each letter or figure must be at least 0.065 inch high).

Style
Two preferences for best read rates:

• Sans-serif font ("block" style letters such as Arial or Helvetica).
• ALL CAPITAL LETTERS.

Spacing
Additional standards for automation flats only:

• Address characters cannot overlap.
• Address lines cannot touch or overlap (0.028-inch clearance preferred).
• Address elements may be separated by no more than five blank spaces.

Examples

Magazine
Usually addressed on front cover

Magazine in Polywrap
Addressed on loose enclosure

Catalog
Usually addressed on back cover

Small Digest
"Vertical" address may cross midpoint if it begins or ends within 1 inch of top edge

Large Envelopes
Horizontal format is fine - "top" is left or right edge

Source:  For more information see the Flats Sequencing Strategy Web page on http://ribbs.usps.gov/.