cancel queued snail mail invoices

cancel queued snail mail invoices

In trying to snail mail invoices last night I received emails stating they could not be processed at that time due to internal problems.  I HAVE to get these invoices out ASAP so will be printing them and mailing them myself.  Meanwhile, I don't want clients to receive a second, identical invoice.  Any suggestions on how to cancel queued invoices?  Also, this isn't the first time I've had problems with snail mail.  Need help. 

Thanks,
Trudy Hibler