A ticket (paper or electronic  eurail pass) is normally requested to be shown before reservations are issued.

That is not to say your friends won’t be able to get a staff member to issue them anyway, it will depend on how persuasive they are and how obliging the staff member is.

There have been several reports in this forum the last weeks that staff at counter in ESpana-for RENFE ask to show pass-working-and even activated for chosen day to travel There was also 1 case where one had to active that day-and then was told NO seats available-and then that day could not be de-activated anymore! It is unclear if this is general policy for all or locally invented. So last sentence of Al_G does hold.

Thank you  Al_G! and mcadv! I know someone who have purchased reservation for an Eurail friend in the past but more recently when my friend tried to purchase my reservation he was asked to show passenger’s eurail pass and passport. 

I was told that RENFE reservations could also be bought in Germany, as long as the paper reservation could be picked up and mailed =to the traveller. Does anyone know if this is accurate?

A bit late, but this is still accurate. It's just that you need a DB staff member who knows how to book these trains. They can't book them the standard timetable-based way but they need to use the train number search.