Does the phrase continue?

[sdraw4]

Is there more to the phrase 'The check is in the mail'?

[darth vader]

The phrase does not continue, that is all there is to it. "The check (cheque) is in the mail" is usually a put-down line to get someone off your back when you owe them money. More often than not the cheque never gets posted, but the debtor can then blame the postal service (and buy him/herself some time) when it doesn't arrive. Sorry if i was being overly informative but it was hard to get the gist of your question

[JohnPPotts]

Usually something along the lines of "I posted it two days ago, First Class. I'm surprised you haven't got it yet. The Post Office, they get worse every year..." and so on until you run out of inspiration.

[Roxy]

'the cheque is in the mail, as is your soul' is in fact the full length phrase

[bigbadben]

Yes there is more to the phrase - it is part of the saying, 'The 3 great lies' : 1) The check (cheque) is in the post, 2) Of course I will still respect you in the morning and 3) No, I won't come in your mouth ....