is:

If the envelope contains ANY Merchandice it is considered a parcel.

Only Documents and paper items are considered a "Letter" by the Post office.

I have mailed many packages that I thought qualified in size as a letter but when I was asked at the Post Office what was inside it, they told me it didnt matter what size it was.... It was a Parcel.

I used to mail 000 mailers from home with just the $64c stamp but then I received about 20 back in the mail saying insuficcient postage.

So while all PO's might see things a little differently, at least the one by my house says even in an evnelope, if it contains a chip, its a parcel.

Doug