Postal Pointers

Where to begin:

Pieces to be mailed must be evaluated by the following criteria:

SIZE (parameters)

1.  SIZE:
Minimum size of any mail is 5" long x 3+1/2" high
POST CARDS can not exceed 6" long x 4+1/4" high
FIRST CLASS cards and envelopes can be up to 11+1/2" long x 6+1/8"high.
Larger envelopes up to 15" long x 12" high  with a maximum thickness of 3/4" must be flexible to go as FLATS.
Non-flexible and over 3/4" thickness go at Parcel Rate.

The postal clerks use a 1/4" slot for envelopes which must be uniform in thickness and flexible. 
A 3/4" slot is for flats which must be flexible.

Automated sorting machines will bend your mail around a 45-degree curve at lightning-fast speeds.

First Class Mail (proper size and thickness) up to 1 ounce currently goes for 49-cents FOREVER STAMP.
The second ounce costs 21-cents, for now.  Each additional ounce requires another 21-cents. 

I have just become aware of this factor.  If the address side of your mail is shiny like plastic, the orange sorting bar code ink will not stick.  Reinforcing edges of envelopes with tape is fine, but covering the bottom 1/2" of either a post card or envelope with anything (TAPE, INK, PAINT, COLLAGE, WRITING, STICKERS, etc.) may cause a problem.  Much of my mail arrives with a white strip at the bottom with a black bar code on it.  (Don't add your own white sticker to out-going mail, my postmistress says; allow the postal sorting system to do so if needed.)

All of the below may require non-machinable postage.

  • plastic bag/envelopes
  • envelopes encased in packaging tape
  • post cards enclosed in cellophane sleeves
  • thicker, heavier, larger, odd-shaped (i.e. Square), rigid mail
  • envelopes and post cards that have any art or writing below the address label

NOTE:  Any mail art not standard thickness, weight, size or shape should be handed over the counter to a postal clerk for weighing and measuring before affixing postage. If you choose to drop your mail in an outside drop box (it could get damp or wet), or an inside mail slot, or have a postal carrier pick up your mail, your mail might bounce back if you haven't considered the factors above. 


--Unless you cover up those metal tabs under the flap of a Kraft envelope instead of using them, your mail will require non-machinable (or another 21-cents) postage.

--Addressing your mail sideways will make it require non-machinable postage.

--Dropping your mail in an outside box or a slot means it will NOT get presorted, and this can lead to delays, damage or returns.  Or postage due when swap hosts receive your mail.

--Unless you cover the lll ll llllll lll llllll sorting neon orange or black bar codes near the bottom (back AND front) when repurposing envelopes which have already gone through the mail, your re-used envelope may bounce back to you, or to whomever it was originally addressed to. 

Corrections or additions may be made to this information as needed.


  1. Honi you are becoming an expert! I did not know about the problems if an address or the bottom portion is covered up. When you mention presorting, are you saying we should always go to a post office to drop our mail?

  2. As far as I know, it's okay to cover the address label with tape. If you want problem-free mailing, I suggest you take any potentially non-conforming mail to a friendly, knowledgeable postal employee who can accurately evaluate your postage needs. Hope that helps? Honi