Win x Linux x Recipient Pile

[Adren]

I´m using the qmail server under linux enviroment but my "costumers" are
using my software under the Windows platform.
My Win software was created in C language and it is a very rush program,thus
it overloads the qmail recipient pile.
So, I had been wondering about a way to retrieve how many messages are
waiting for delivery (from qmail server).
Do you have an idea to do that ?