I don't know of a way to do that.  One alternative would be to add a text object in a really big font to the Page Header or Report Header section of the invoice in Crystal Reports.  The text would be something like, "DO NOT USE", and it could conditionally print if the order amount is less than a specified amount.  The people processing the orders would look for those words in the header section and discard them before mailing.

Not Ideal but a viable option. Thanks for your input!

What you could try is go into the Report Expert and exclude invoices where TaxableAmount+NonTaxableAmount =0.00

I'd be careful suppressing entirely, because that can affect Paperless PDF's. 

A simple fix would be to suppress the mailing address if the invoice total is less than $1.  Then you can't mail it out.

Just a theory but it might work.  Add a UDF that computes the balance of the invoice.

In many places in Sage 100, a UDF automatically becomes a field you can select by when printing.  Can't say I have ever tried it for an invoice.

Right on Tom! Create a numeric UDF on SO Invc Header called Minimum_Amt_For_Send or something. Add that to Totals tab / panel of SO Invoice Entry screen. Invoicing person can key in the invoice balance manually or via script into the UDF. Then in Invoice Printing, in the Selection grid, on UDF_Minimum_Amt_For_Send, set the Operand to Greater Than and Value to 1.00. The  > 1 will filter the record selection in the worktable before Crystal even processes it. This way no changes are required in the Crystal form for the SO Invoice.

Thanks for the idea Tom. I also thought about doing this, but for Sales Order > Invoice Printing, I don't think there is a way to filter by a UDF. The only selections available for filtering are:
    Invoice Number
    Warehouse Code
It seems like we should be able to add different filter fields, but I've never seen an option for that.

As you say, it doesn't appear to work for printing forms.    It does appear to work for reports.

Two other thoughts.

1.  Enable paperless office to e-mail invoices.  That save a lot of paper and postage!   I personally e-mail all my invoices.   I set my clients up for e-mailed invoices by default.  If someone complains, you can turn it off customer by customer.  I've never had anyone ask to have me stop.  I think this is called do it and then ask for forgiveness.  ;)

2.  There is a check box when entering an invoice for whether you want to print the invoice or not.  That is normally used if you have a method of doing invoices external to Sage 100.  Of course I would think you would want to have some record of the invoice somewhere for the client to see.

We have an enhancement that will set the printed flag to prevent it from printing when the invoice is $0 upon accept. There is also a flag added to printing that will allow you to toggle include $0 invoices.  If you have any interest let me know your version and I can get you more information.

We would be interested in this option. We are running Sage 100 (2018)