Are printable envelopes made of special paper?
No. Printable envelopes are made from the same paper as normal envelopes. They can be custom made from any kind of paper. The only restriction here would be vellum envelopes. Low weight vellum does not take printing easily and therefore cannot be used for printable envelopes. Printable envelopes are first printed, cut and then folded and glued into envelopes as per the specified sizes.