Steam is one way to unseal an envelope: boil water and hold the envelope in the steam. Only use this method on envelopes addressed to you; opening mail that doesn't belong to you is a federal crime.
- Boil water
Fill a tea kettle or electric boiler half-full of water. Turn it on or place it over a heat source, as appropriate, and wait for the water to boil so steam escapes through the spout.
- Hold the envelope in the steam
Wear a glove to protect your hand. Hold the envelope in the column of steam for about 15 seconds to dissolve the glue, then open the envelope.
- Re-seal the envelope
Run a thin bead of glue along the inside edge of the envelope flap. Press the flap down to reseal the envelope.