Postal Pointers

(The information below is as complete as I can make it.)


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" wide x 4+1/4" high
FIRST CLASS cards and envelopes can be up to 11+1/2" wide 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.  Beyond that, your mail becomes a "package" and costs more to send out.

Automated sorting machines will bend your mail around a 45-degree curve at lightning-fast speeds.  Any loose collage elements may lift off or be damaged.

First Class Mail (proper size and thickness) up to 1 ounce will cost 55-cents as of January 27, 2019 .  A FOREVER STAMP will automically assune the new value.
The second ounce now costs 15-cents.  Each additional ounce requires another 15-cents. 
There are several "Two Ounce" or "Nonmachinable" stamps in print at this time. 

I have just become aware of this factor.  If the address side of your mail is shiny like plastic, the orange or black 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 nonmachinable postage.

  • plastic bags/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 into 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.  Or your recipient may have to pay any postage shortages when he/she receives it.


--Unless you cover up those metal tabs under the flap of a Kraft envelope instead of using them, your mail will probably require non-machinable postage of 70-cents (or a FOREVER stamps plus 15-cents) postage.

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

--Dropping your group swap mail art in an outside collection box or a slot means it will NOT get presorted, and this can lead to delays, damage (think SNOW or RAIN) or postage due when swap hosts receive your mail.  Best scenario:  hand it over the counter if at all possible...

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

POST CARDS (and other mail) are read from the bottom up by those impersonal automated sorting machines.  If you put your return address at the bottom left on a post card, you may
very well receive your own art back through the mail.  Return addresses are supposed to be in the top left-hand corner, so I was told.

AS OF 10/03/19

Anything weighing over 10 ounces
Anything thicker than 1/2"
and having regular postage stamps on it,
May not be mailed out from a mail box or postal drop
It must be handed across a postal counter,
have postal strips affixed from an approved

online source of US postage.

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

    The illustration on this page supports the return address on the upper left :-)
    Also, to keep address formatting up to date, USPS asks we
    -OMIT PUNCTUATION, including commas and periods (unlike we were all taught years ago)
    -USE THE ZIP+4 whenever possible