There are many times in life where you may find yourself needing to open and reseal an envelope without anyone knowing. While many people instinctively think of doing this in order to view someone else's mail, that's actually a crime and should be avoided. That being said, there are occasions where you may need to get into a sealed envelope that won't break the law.

For example, you might start to send out a letter with a presorted mail envelope before realizing you wanted to add something to the document. Or, you might want to send a letter back to the sender without letting them know you read it in the first place. An employee of yours may have sealed a "Happy Retirement" card for another employee without knowing that you wanted to include a gift card in the envelope. In these cases, you can choose to channel your inner secret agent and covertly open the envelope and reseal it without anyone being any wiser.

Freezing Open an Envelope

Most glues, particularly those used on envelopes, can't hold up to extreme temperatures. By freezing the glue, it will largely inactivate it so you can use a knife to break any remaining seal.

Start by putting the envelope in a plastic bag so it doesn't get damaged in the freezer, even if something spills on it. Then, leave the envelope in the freezer for about four or five minutes. Immediately use a knife to pull the flap up from the rest of the envelope while the glue is still frozen.

Because the glue just hardened in the freezer, it should still be usable when you're ready to seal it again. Just lick the envelope seal or use a sponge to reactivate the glue, close the flap and press down. If it doesn't seem to be sealing properly, use a glue stick or a cotton swab dabbed in liquid glue to add a thin layer of glue where the seal should be.

Steaming Open an Envelope

This is the method most people have heard of because it has been featured on tons of sitcoms where teens need to check something the school sent to their parents before their parents read it. In reality, this method should ideally only be tried if freezing fails because it's possible the steam may warp the envelope paper and the contents inside. If the paper is too wet, be sure to lay it on a flat surface to dry.

The source of steam can be just about anything, but most people find the steam from a kettle or a mug filled with freshly boiled water to be the easiest to work with. Some people claim that using an iron on low heat with the steam on is actually more effective as there's less moisture, reducing the chance of water damage. Once things start to loosen up a bit, use a knife to gently pry the flap up, using more steam if you notice any resistance.

To reseal the envelope, use a glue stick or liquid glue applied to a cotton swab, as the steam method does make the glue on the envelope no longer usable.

Microwaving Open an Envelope 

Microwaving an envelope is risky and should only be attempted if the other two methods fail or aren't possible in a given circumstance. Because the heat from the microwave can cause the paper to catch fire, be extremely careful and only microwave the envelope for 10 seconds to start and then run it again for five seconds at a time, checking each time to see if the seal has loosened by gently trying to run a knife under the flap.

To reseal an envelope after microwaving it, use a glue stick or a thin layer of liquid glue just like you would if you steamed it open.