This series was instituted as a ready reference resource by the former NSW Historical Section. Consisting of over 3000 manilla folders kept in alphabetical order, the series deals with post offices, receiving offices and telephone offices in NSW, as well as with some large or significant post offices in other parts of Australia. Some of the files in the series would seem to have been numbered so as to correspond with the numbers allocated to post office histories prepared by the Historical Section.

Put together from primary source material despatched to Australian Archives some years ago, these histories are to be maintained by Australia Post as per agreement with Archives' Officials. The files were raised by the Historical Section either as documentation came to hand, or in response to enquiries from the public. They contain, among other things, temporary employee staff cards and permanent employee staff cards (SS 47S0,) letter delivery cards and "miscellaneous" cards. In the files there can also be found original documentation and copies thereof, plans of buildings and settlements, and press items. In the case of larger Post Offices, this material is stored in separate files.

The Historical Section did not keep the contents of files in strict chronological order. These records ceased to be maintained following the closure of the section in late 1988.