If the total outstanding amount was mailed on the 23 of Dec when will you get it?

If the total outstanding amount was mailed on the 23 of Dec when will you get it?
The answer depends on a few variables.

If you placed the total outstanding amount in a mailbox, it depends on when the mail was collected that day. It may not have been collected until the 24th.

Another variable is how far the mail is travelling. If it's across town I could have received it Saturday the 26th. If it's travelling from a nearby town I could have received it Monday the 28th. If it's travelling across the country, I may not get it until Wednesday the 30th.

You should really give yourself extra time to mail the total outstanding amount to allow for weekends, holidays and delivery time, because the only thing that matters to me is when I get it and if I get it before the due date.