You can still enjoy tea though, while you do spycraft.

In almost every classic spy movie, an operative opens a highly classified letter by holding the envelope over a boiling kettle to melt the glue.

The FBI’s Operational Technology Division (OTD) calls that amateur hour.
Within the OTD is a highly specialized, secretive unit known informally in the intelligence community as “Flaps and Seals.” Their entire job is surreptitious entry into packages, secure mail, and luggage.

They don’t use steam—it warps the paper fibers, bleeds the ink, and leaves obvious evidence of tampering. Instead, these technicians operate like microscopic surgeons. They use precision micrometers to measure the exact thickness of an envelope before opening it. They deploy proprietary chemical solvents that dissolve commercial adhesives instantly without leaving residue.

They can intercept a sealed diplomatic pouch, extract the contents, photograph them, clone the digital drives, and re-seal the package so flawlessly that even the person who licked the envelope wouldn’t know it had been touched.