About product and suppliers:
            2,275 proof envelope products are offered for sale by suppliers on Alibaba.com, of which mailing bags accounts for 58%, paper envelopes accounts for 1%. 

A wide variety of proof envelope options are available to you, such as gift envelope, business envelope. You can also choose from window envelope, wallet envelope proof envelope, as well as from ce / eu, fda proof envelope, and whether proof envelope is waterproof, anti-curl, or non-toxic. 

There are 2,275 suppliers who sells proof envelope on Alibaba.com, mainly located in Asia. The top countries of suppliers are India, China, and India, from which the percentage of proof envelope supply is 1%, 99%, and 1% respectively.