differentiated by three factors - (1) weight, (2) size and (3) destination (within or out-of-state).
Yes, Aussie Post Offices have a stiff cardboard template, near the desk
and when I post eBay
sales etc, they always try the article to fit through the appropriate slot.
Do you know what happened to mail that measured less than the stipulated 88mm by 138mm?
Can only speculate.
1. Returned with an explanation handstamp?
2. Processed and delivered (got through)
3. Refused at counter.
I have never seen that size in 18 years, that is a very small envelope.
I have one here, delivered yesterday ( eBay
) 130 x 160 mm
(A cut down manila envelope)
That is one of the smallest I have had for a while.
The current approved Aussie DL envelopes are very fragile and thin
understandable regarding fuel / climate change.
But inserting cardboard stiffeners defeat the reasoning.
Hard to find a suitable stiffer DL envelope sadly.