An envelope that has been sealed with any kind of gum-type adhesive can be also termed as a “Gummed” envelope. This type of envelope generally has a water-soluble gum or glue strip on its flap. This type of envelope can also be sealed mechanically using a specialized mail sealing machine. When an envelope or a mail is inserted inside this machine, the gum or glue present on the flap is moistened automatically and then preseed closed using a pressurized mechanism. After the closure, the envelope with its contents is ready for mailing or to be shipped.