A security envelope is a security-perforated envelope that the sender can use to ensure the confidentiality of messages. The security printing on the inside of the envelope prevents the text from being visible through the envelope. It is also impossible to open and reseal the envelope without leaving obvious signs.
Security envelopes are, for example, suitable for sending contracts, patient information, and other sensitive letters. The envelopes are available for domestic and international mailings in C4/E4 and C5/E5 sizes.