Central Mail Services offers a one-stop shop for all your bulk mailing needs. We do automated insertion, hand insertion, and self mailers. There must be a minimum of 200 pieces or 50 pounds, all identical, in your bulk mailing, and we require a completed requisition stating your specific instructions and departmental mailing code number as well.

The Postal Service requires every bulk mailing to conform to the following specifications:

ADDRESSING

• ZIP Codes are required on every address. Missing ZIP Codes will delay your mail.
• Mail pieces must be sorted in ascending ZIP-code order. Mark boxes or trays indicating the order, for example, "1 of 5", "2 of 5", and so forth, if you have five boxes of mail.
• Only pieces sent to a U.S. address may be included. International mail may not be mixed with domestic bulk mail. Check our list of states, possessions, and territories if you are unsure.
• A department's full return address is required on each mail piece. U.S. Postal Service-approved University of Iowa return addresses are posted on this website and published in the UI directory (herd book). An improper return mail [addressee?/address] will not be accepted by the Postal Service.

BAR CODE
All letter-size reply cards and envelopes (business reply, courtesy reply, and metered reply) enclosed in a bulk mailing must bear a correct delivery-point bar code for the address to which the mail piece is to be returned.

CLOSURE
Don't use staples to close your mail - they catch on machinery and cut hands. Tabs made of paper or light plastic are preferable. Mail Service has tabbing equipment that places tabs according to postal standards.

• Endorsements must have a minimum 8-point type size,
• stand out clearly against the background, and
• have a 1/4-inch clear space above, below, and on both sides.
• They must be located below the return address, immediately above the delivery address, and either left of the postage area and below any rate marking or below the postage area and rate marking.

INDICIA/PERMIT IMPRINT
A block of text indicating that postage has been paid must be printed or imprinted by a meter on each mail piece.

PAPER AND INK
Use dark ink on light paper for high-contrast readability. Light-colored ink on dark stock and fluorescent paper and ink do not work well.

• Letter-size
  Minimum: 5" wide x 3-1/2" high, .007" thick
  Maximum: 11-1/2" wide x 6-1/8" high, .25" thick
• Flat-size
  Minimum: 11-1/2" wide x 6-1/8" high, .25" thick
  Maximum: 15" wide x 12" high, .75" thick
• Postcard
  Minimum: 5" wide x 3-1/2" high, .007" thick
  Maximum: 4-1/4" wide x 6" high

WEIGHT
The weight limit on a nonprofit letter is 3.2873 ounces (0.2055 lbs.), the regular rate letter weight limit is 3.3087 ounces (0.2068 lbs.). Pieces over these weight limits are mailable at the higher rate for flats.