In Russian Empire, most of the services such as post office, fire brigades or railways were state property and thus has been manned by people who were considered state officials. Furthermore, said offices much like the state administration has been organised in a way similar to armed forces, with clear-cut progression of ranks parallel to the one used in military.. Conversely, all postmen or railway administrators (conductors, stationmasters etc.) were issued in uniforms similar to the ones used by military personnel, often complete with weapons, sabers of spadroons being most common.

Postmen and telegraphists, especially those working in the cities, were carrying dirks as a part of their uniform [see picture 1, 4 and 5]. This regulation has been withdrawn in 1867, as weapons were deemed unnecessary and apparently only contributed to faster wear and tear of the uniform (this implies indicate that they were rarely, if ever used for self-defence). On the other hand, postmen traveling between towns and villages, were usually carrying a light cavalry saber, even when the personal weapons ceased to be issued to most postmen [see pictures 2-3, as they show uniforms from 1880s complete with sabers] and it was a part of their uniform until the end of 19th century. This was used both due to regulations (such postmen were technically cavalry and their uniform reflected this) and for self-defence, as postmen were often carrying money and were usually traveling alone on horseback or accompanied by a yamschik (peasant tasked with various services, most commonly transport) when travel warranted the use of horse cart or sleigh. In pictures [6] and [7] you can see postmen being armed with sabres. The former depicts basically the same outfit described by Chekhov in 'The Witch': an armed postman (in the rear, in white winter uniform) and a yamshchik (coachman) in black. In the latter you can also clearly see armed postman (first on the right, with a noticeable Imperial crest on the left side of his chest) closing the line of baggage carriers. Pictures [8] and [9] also show armed postmen working in the desert regions of Russian Empire.

[1] http://s00.yaplakal.com/pics/pics_original/6/1/0/7192016.jpg
Russian picture of the city postman, taken in the 1860's by William Carrick in Sankt Petersburg.

[2] http://grafika.ru/iblock/d06/d06ecf679f10557b7bd7b06409c112ee.jpg
Postmen uniforms, in: 'Ministry of Internal Affairs - Historical Essays - Post and Telegraph Office in 19th century'*, Sankt Petersburg, 1901, p. 12.

[3] http://grafika.ru/iblock/10c/10c203b1bbbc63dc9659c1676b8b64c7.jpg
Postmen uniforms. Ibidem, p. 13.

[4] http://grafika.ru/iblock/178/178684389bf3f75748cf34d05f7c56db.jpg
Telegraphist's uniform, 1858. Ibidem, p. 163.

[5] http://grafika.ru/iblock/2e2/2e27bd2e74df06274ab992107ccb8bce.jpg
Uniforms of low-ranking members of telegraph service from 1855, 1861 and 1885. Ibidem, p. 164.

[6] https://imgur.com/a/6jN373F
Transport of mail by three-horse sleigh. Ibidem, p. 45.

[7] https://imgur.com/a/1m9tTuW
Transport of mail by foot in the Caucasus Mountains. Ibidem, p. 46.

[8] https://imgur.com/a/AgZe2NG
Transport of mail by a camel-drawn cart, Ibidem, p. 48.

[9] https://imgur.com/a/q689NIj
Transport of mail by camel in bags. Ibidem, p. 49.

*Complete book (in Russian) is available here: https://www.runivers.ru/bookreader/book58653/#page/3/mode/1up