On Sundays there is a mail clearance across the country.That is designed to provide mail for Monday deliveries locally and to start interstate mail on its journey. The large mail exchanges all operate to provide the service,

It happens on aboy 42 sundays each year.

On a few occasions each year when there is a public holiday on a Monday there are no local deliveries. therefore the mail boxes are not emptied on Sunday as the mail woudl only clog the sorting centres and mail exchanges and not be sorted until Monday night. when there will be another collection.