AUSTIN (Nexstar) — Postal workers across America are nearly done processing hundreds of millions of packages nationwide, but what happens to the packages that people try to send containing prohibited materials?

When you bring your mail to the post office, employees will ask if there are any liquids, flammable, or hazardous material inside the package. It’s your responsibility to make sure anything you mail complies with what’s allowed.

Each local post office has an area where non-mailable items are detained.

“USPS personnel completes required paperwork and contacts the sender or addressee by phone to advise them of two options,” United States Postal Service spokesperson Becky Hernandez said. “They may retrieve the item within two days, or they may come to the facility within two days to correct any deficiencies in labeling, markings, packaging, etc.”

“If the customer can not be reached by phone, a certified letter is mailed, advising them of their options,” Hernandez explained.

If the mailer or addressee does not respond, the mail is considered “abandoned,” Hernandez said.

“(It) is properly disposed of in compliance with federal, state, and local environmental regulations,” she added.

Mail may be flagged if the letter or package is stained or is leaking. According to a USPS brochure, reused packaging and boxes are only acceptable when all markings and labels are removed or completely marked out.

“Regardless of what is actually inside your package, markings or labels for hazardous materials may result in delivery delays or a package return,” the brochure stated.

USPS categorizes prohibited mail by:

  • Explosives: fireworks, ammunition, fuses, model rocket engines, automobile air bags
  • Gases: aerosols, hairspray, scuba tanks, compressed gas containers, lighters
  • Flammable liquids: fuels (gasoline, butane, propane), items that contain or used to contain fuel (lighters, propane cylinders, used gasoline tanks), some paints and inks, furniture varnishes, perfumes
  • Flammable solids: matches, signal flares
  • Oxidizers and organic peroxides: oxidizing liquids, nitrates, swimming pool chemicals, peroxides
  • Toxic materials and infectious substances: insecticides, pesticides, pepper spray, infectious substances, sharps, patient specimens
  • Radioactive materials: scientific instruments, productions requiring a radioactive warning label
  • Corrosives: bleach, ammonia, batteries, drain cleaners, mercury, oven cleaners
  • Miscellaneous hazardous materials: magnets, dry ice, self-inflating life-saving devices, lithium and lithium-ion batteries.

There are some exceptions, and if you have questions, you’re encouraged to contact your local post office.

USPS anticipates delivering nearly 15 billion pieces of mail and more than 900 million packages between Thanksgiving and New Year’s Day, totaling almost 16 billion deliveries during the holiday season, the agency reported last week.