Definition of "mail service" [mail service]

• The system whereby messages are transmitted via the post office (noun)

WordNet. Princeton University. 2010.

• "Telegraph companies, express companies, railway companies, the excellent mail service and the like out-despatch any conceivable agent ” except Petherick."
• ""I'd made such a point of that with Mrs Spears that I couldn't hardly leave before that was finished, but then I got away and I went into Cairns one Wednesday with John Duffy on the Milk Run" - I found out later that he meant the weekly Dakota air mail service - "and so down to Brisbane."