I don't use padded envelopes, as the ones I receive still are bent by postal workers. Though if people use rigid top loaders inside them, this seems to be ok.
I use 6x6" rigid CD envelopes for my ACEOs.
I put my ACEO in a sleeve, together with an COA (certificate of authenticity) and a thank you (2 x 4x6" index cards. I buy the envelope on ebay in bulk for what works out to about 17 cents each. They post in the USA for .52 cents. I make sure the back of my ACEO has my unique numbering, title, © (copyright symbol) my full name and year, my signature, medium, my website, my ebay id.
I don't get delivery confirmation. The cd mailer is too thin to qualify. If I needed to I could put a packing peanut inside to 'fatten' it so I could.
Happy ACEO'ing. :)
Regards,
Jillian
~Jillian
artist, Jillian Crider
... google me!