printing an email invoice overwrites bill header
Set up an XML invoice with the Invoice Media set to "Email Invoice as Attachment". Run the Finalize and Print process from Generate Invoices > Non-Consolidated, and set the "Email Invoice Options" to "Print Only" on the run control. The F&P process goes back and overwrites the bill header to change the Invoice Media to Print Copy. Now the bill is finalized, and it will be "Print Copy" forever -- there's no way to tell it to email a reprint later, for instance.
Personally, I don't think individual users' run control choices should be mucking with the bill header -- the bill header should stay however it was set no matter how a user chooses to run a particular individual job.