We are having a huge issue with the NetSuite ability to automatically email AND fax Purchase Order to vendors. 

Setup -> Accounting -> Accounting Preferences
On the “Order Management” tab, under “Drop Shipment” we selected (checked off) both “Automatically Email Drop Ship P.O.s” and “Automatically Fax Drop Ship P.O.s”
On the vendor record of each drop ship vendor, we either selected (checked off) either “Send Transaction Via” “Fax or “Email” depending on the vendors preference. 

We found that for each vendor that contained a Fax number AND Email address that NetSuite BOTH emailed AND faxed the PO even though only ONE (fax or Email) was selected on each vendor record as the preferred method to send transactions. We called Support and were told that this is an issue but the work around would be is to remove the fax number for the emailed vendors and to remove the email from the faxed vendors.