A mailbomb or letter bomb is a bomb sent via the postal service, and designed to explode when opened, injuring or killing the recipient, usually someone the sender has a personal grudge against, or more indiscriminately as part of a terrorist campaign.

Bombs delivered by mail can often be recognised because they arrive in suspicious packages or unusual looking letters. The Police and security consultants can advise how to recognise possible mailbombs.

Anyone suspecting that they have received a mail bomb is advised to:

  • Lower the article to a level surface.
  • Do not disturb the article. Do not open it or cut any strings.
  • Do not place the article in a confined space. Do not immerse in water or cover the article.
  • Do not permit anyone to touch or move the article. Leave it where it is.
  • Clear the area immediately of all people. Evacuate the building.
  • Leave doors and windows open, but do not linger to do this. This can reduce blast damage but it also provides a clear path for bomb disposal equipment.
  • Do not operate mobile phones or portable radios until clear of the area, as these may trigger an explosive device if operated near by.
  • Call the Police once clear.

A related threat is mail containing unidentified powders or chemicals. In many cases, these turn out to be harmless, and often sent as a joke or hoax threat. However, until the substance can be analysed in a laboratory it may present a hazard, so Police or environmental authorities may close the affected areas. This often is the intended purpose of the sender.

see also Unabomber, Crank call, Bomb threat


In Internet usage, a mailbomb is a form of net abuse consisting of sending huge volumes of E-mail to an address in an attempt to overflow the mailbox or overwhelm the server.