You Got Murder

""Special delivery, a bomb. Did you order one?""

- Inspector Clouseau, Revenge of the Pink Panther

""My correspondence [...] is, as you know, a varied one, and I am somewhat upon my guard against any packages which reach me.""

- Sherlock Holmes, brushing off a particularly nasty close call

When the postal service is used to kill someone, usually by letter bomb, biological weapon, or some kind of magic that uses the written medium. Sometimes, an e-mail or other New Media messaging device is used in place of an actual letter or package.

One of the forms Somebody Set Up Us the Bomb can take.

Anime and Manga

 * In the first episode of Full Metal Panic? Fumoffu, Sousuke detonates his shoe locker when he discovers it's been tampered with, under the assumption that someone planted a bomb in it. Of course, it was just a love letter, but he cites a case in which someone was killed by a bomb in the mailbox. This happens several more times.

Comic Books

 * A certain special parcel delivered to Gotham City district attorney Harvey Dent and his wife Gilda in The Long Halloween.

Card Games

 * One of Magic: The Gathering's joke supplements contains a 'letter bomb' card, which gets shuffled into the opponent's deck and hits him for massive damage when drawn.
 * There was a legit card that has a similar damaging effect though it worked by poisoning (turning face up then being shuffled into their deck) one of their cards rather than being planted.

Film

 * Jingle All the Way has fun with this. Myron, a disgruntled postman, threatens a radio DJ with a package that he claims is a bomb which he discovered in the mail and kept for use in an emergency. It accidentally falls out of his hand and is revealed to be...a music box. Later, when the police show up, he threatens them with a different package. When the police let him go a retired bomb squad officer claims it's just a "harmless Christmas package", which blows up in his face, only turning his face black. When Myron hears the explosion he is surprised and disgusted that somebody really had sent a bomb through the postal system.
 * Blazing Saddles: "Candygram for Mr. Mongo!" "Mongo like candy" *BOOM* (He survives, but presumably only because he's ridiculously strong.)
 * In Magnum Force, Harry and his assistant both have their mailboxes wired with explosives when the mailbox key is turned.
 * In the Swedish film Sprängaren (adapted from the novel by the same name), the murderer sends the protagonist, who is a journalist, a bomb package. Subverted in that
 * The hitman Trabucco (Walter Matthau) disposes of one of his victims this way, early in the film Buddy Buddy.
 * The Inspectors, a film about US Postal Inspectors, follows the investigation of a mail bomb murder (interestingly enough, the Postal Inspectors are a Real Life law enforcement agency... in fact, they are the oldest federal law enforcement agency in the United States.)

Literature

 * Erast Fandorin receives a bomb package on the day of his marriage.
 * The Stephen King short story "Everything's Eventual" centers around a young slacker hired by a mysterious firm because he has the ability to compose "glyphs" that can drive the viewer to suicide. They sends him a list of names and addresses, and he puts the glyphs on letters.
 * In the book A Death in Vienna by Daniel Silva, the death is caused by a letter bomb sent to an ex-Mossad agent turned Nazi hunter.

Live Action TV

 * Jonathan Creek had a writer poisoned with a hallucinating drug contained in a enclosed letter glue from some fan mail. Once he licked the letter he went a bit nuts and managed to stab himself in the back with a sword.
 * Monk put a spin on this one, in the episode "Mr. Monk and the Sleeping Suspect". Monk is working on a mail bomb murder case, and must figure out how his prime suspect was able to send the bomb while in a coma. And, of course, he does.
 * One episode of The Avengers had letters containing an enhanced cold.
 * In Warehouse 13, a teenaged Stalker with a Crush uses this as his method of revenge once he gets his hands on Poe's quill pen.
 * In the Law and Order: Criminal Intent episode "The Saint" a social worker is killed by a lye bomb delivered in the mail.
 * Also in the Law and Order episode "Big Bang", a physics professor's wife is killed by a letter bomb. While the bomb itself was not meant to be lethal, the letter opener the victim used was blown into the woman's throat, killing her.
 * Used in an episode of Early Edition.
 * NCIS had DiNozzo contract pneumonic plague this way.
 * Dads Army. The platoon is given a mission to test security at an army base, and decide to infiltrate disguised as firemen. As usual things go wrong and they end up fighting a real fire elsewhere. A high-ranking officer arrives and tells Mainwaring not to worry as his 'other plan' worked. Turns out Wilson sent a fake bomb in the mail.

Tabletop Games

 * Dungeons and Dragons has explosive runes (as mentioned in the OotS example).
 * D20 Modern has rules for sending any spell via email to effect the person who opens it (or even teleporting an assassin to them via IM for a sneak attack).
 * The anger mages of Unknown Armies have a spell that lets them enchant a letter, note or e-mail with another one of their spells (which can include damaging spells).
 * This is the M.O. of the villain Death's Messenger from the Dark Champions sourcebook Murderer's Row.
 * Exalted has Bureaucracy Charms that allow you to write a Strongly Worded Letter with such venom that it actually does damage to the reader.

Video Games

 * Eternal Darkness had an assassination attempt at Charlemagne by sending him a scroll with a magick attack. Unfortunately, Anthony opens it first and spends the next 600+ years cursed in agony locked in a room. (And Charlemagne still gets killed.)
 * One case in the Ace Attorney series involved one of these. Specifically,.

Web Comics

 * Order of the Stick: I prepared Explosive Runes this morning.
 * Ranger's arrows were delivered home with their momentum still intact.

Western Animation

 * One Batman the Animated Series episode had the scarecrow dosing people with contact poison by telegram. It was only his patented "fear toxin", though.
 * In an episode of Tale Spin, Shere Khan sends some pirate allies a special letter after they fail in their shared evil plot. Hint: its ticking and its NOT a clock.
 * Parodied in The Venture Brothers. The Monarch mailed Dr. Venture a live cobra but by the time Dr. Venture actually got around to opening his mail, it was dead.

Real Life

 * Anthrax
 * The Unabomber
 * One of the first Real Life letter bombs was constructed by Martin Ekenberg in 1904. He tried to kill a former employer and frame the Social-Democratic party...
 * A Darwin Award nominee- the attempted letter-bomber who neglected to pay enough postage. The letter was Returned To Sender... and so was he.
 * YEEEEAAAAAAAAAH!