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Possible Indicators that a Delivered Item Might be of Concern

Last Updated 04 May 2021


Many of these indicators are quite general. One alone will not necessarily constitute a cause for concern. Their individual relevance will vary with context, e.g. depending on the nature of the organisation's business, and in light of the current threat and Response Level. Any suspicions should be considered in combination with a thorough risk assessment.

General Indicators

General indicators that a delivered item may be of concern include:

  • unexpected item, especially if hand delivered 
  • a padded envelope ('Jiffy Bag') or other bulky package 
  • additional inner envelope or other contents that may be difficult to remove 
  • labelling or excessive sealing that encourages opening at a particular end or in a particular way 
  • oddly shaped or lopsided 
  • envelope flap stuck down completely (normally gummed envelope flaps leave slight gaps at edges) 
  • marked 'to be opened only by...' 'personal' or 'confidential' 
  • item addressed to the organisation or a title (rather than a specific individual) 
  • unexpected or unusual origin (postmark and/or return address) 
  • no return address or return address that cannot be verified 
  • poorly or inaccurately addressed address printed unevenly or unusually 
  • unfamiliar writing or unusual style 
  • unusual postmark or no postmark 
  • more stamps than needed for size or weight of package 
  • greasy or oily stains emanating from package
  • odours emanating from package.

Explosive or incendiary indicators

Additional explosive or incendiary indictors include:

  • unusually heavy or uneven weight distribution 
  • small hole(s) in envelope or wrapping.

"White powder" indicators

Additional chemical, biological or radiological (CBR) indicators include:

  • powders, liquids emanating from package 
  • wrapping stained by liquid leakage 
  • unexpected items or materials found in package on opening or X-raying (loose or in a container) such as powdered, crystalline or granular solids; liquids; sticky substances or residues 
  • unexpected odours observed on opening 
  • sudden onset of illness or irritation of skin, eyes or nose.


Mail Screening Matters campaign

NPSA's "Mail Screening Matters" campaign contains a variety of useful resources to help increase awareness around postal security and complement information contained within PAS 97 Mail screening and security - Specification. This includes a poster and factsheet (in print and digital format) to raise awareness around possible suspicious indicators on items of mail.


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