Royal Mail have helpfully published a list of things they instruct their postal workers to check for to find 'suspect packages'.Most of them are common sense, but you may find it interesting reading nonetheless. I imagine postal inspectors have a more comprehensive set of instructions, this is probably for the general staff.Quote== Quick Guide To Dealing With Suspect Items eg Postal Bombs, Anthrax etc. ==Recognition of a Suspect Item: Dimensions: A letter bomb is unlikely to be less than 3 mm (1/8 inch)thick, or weigh less than 43 grams (1 12 ounces). Balance/Weight: Is the packet evenly balanced? Lopsided packagesshould be treated with suspicion. Packages that are disproportionatelyheavy for their size could contain an improvised explosive device (IED). Holes or Stains: Packages with grease stains or pin holes in the wrappingshould be treated as suspect. Smell: Some explosive materials smell of marzipan or almonds. Noise: Ticking or hissing sounds may indicate the presence of an explosivedevice. (!) (xD) The Flap: Is the wrapping completely stuck down? The absence of small gaps are left at the end of the flap might indicate a suspect item. Type of Envelope: Experience has shown that postal bombs are usually found in "Jiffy" bags or similar types of envelope. Packaging/Postage: Has an excessive amount of wrapping or sealing material been used or has an excessive amount of postage been paid? (To avoid any possibility of delay or enquiry due to underpayment) Contents 1 : If, in addition to other indicators, (balance, weight, packaging etc ) the appearance suggests that the package could contain a book or videocassette it should be treated as a possible postal bomb or IED. Contents 2: If a powdery, granular or sand like substance, residue or liquid can be seen on the outside of the item or leaking from it, the item should be treated as suspect. Markings: Restrictive endorsements such as Personal or Confidentialmay indicate a suspicious item.