Secure an Envelope

If you’re worried about the envelope opening on its own, people opening and then resealing your mail or someone reading the content through the envelope, try these methods to make it more secure. Even though you can’t guarantee that someone won’t rifle through your mail, seals and special envelopes will at least make it apparent when they do. This can go a long way in preventing or at least recognizing identity theft, violations of your privacy, or direct theft of your mail content.


Preventing the Envelope From Opening

  1. Use a sticker seal. Placing a seal over the envelope flap is a great way to provide some extra security. Seals specifically designed for envelopes will be difficult to remove and place back on. Therefore, if someone does open the envelope, the broken seal will be proof.
    • You can find these seals at any office supply store. A regular sticker won’t stick to the paper as well as a postal seal.
  2. Use a self-sealing envelope. Envelopes with a clasp, strip removal, or string are less likely to open on their own. They can be found at an office supply store.
    • These envelopes may still be opened intentionally so you’ll want another security mechanism if you’re concerned about this.
  3. Use a wax seal. A very old-fashioned way of securing envelopes is to drip melted wax over the flap and let it dry. A wax seal will make it virtually impossible to open the envelope without ripping it. You can find sealing wax at any stationery store and most office supply stores.[1]
    • Most sealing wax comes in bars with a wick in the middle, much like a candle. Light the wick and hold the bar over the flap until a small amount of wax accumulates. The appropriate amount of wax should be able the size of a quarter.
    • Some sealing wax comes in small pellets. Place one in a microwave-safe dish and nuke it for about 30 second. Then slowly drip it over the flap.
    • You could also purchase a seal stamp that leaves a distinctive shape in the wax.
  4. Use tape or glue. If you don’t have a seal, you can use scotch or masking tape to secure the envelope. Double-sided tape is most ideal. You can also use any household adhesive like rubber cement or crafts glues.
    • If you only have one-sided tape, fold it back on itself so that the sticky side is pointing out.
  5. Use nail polish. A lesser known solution is to apply nail polish to the adhesive strip rather than licking it or wetting it with a sponge. Nail polish won’t wear off if someone tries to steam the envelope open. [2]
    • Use the brush that comes with the nail polish to gloss a thin layer over the adhesive strip.

Preventing People from Seeing Through Your Envelope

  1. Wrap the content in paper. Take a plain piece of paper and place the letter, check, or whatever else you’re mailing in the middle. Fold the paper into three or four parts, depending on the size of the envelope.
    • A similar option is to place your content inside a greeting card and then place the card in the envelope.[3]
  2. Use a security envelope. Security envelopes will have a lining substance that makes it more opaque. These envelopes usually have unique colored patterns.[4] They can be found at any stationer's store, some mobile stores or office supply stores and should only be a little more expensive than regular envelopes.
  3. Use two envelopes. Another simple way to prevent people from reading through the envelope is to use two. In addition to your regular envelope, get another one with slightly larger dimensions and place the first one inside of it.