Epson 5000 - Manual (Page 101)

7. Set the envelope levers on each side of the cut-sheet feeder.
Pull the levers forward for single sheets of paper or push
them back for envelopes.
8. Push the paper-set levers back to clamp the paper or
envelopes against the guide rollers.
Note:
Even when the cut-sheet feeder is installed, you can also insert single
sheets using the front paper slot or the slot between the paper guide
and stacker.
The cut-sheet feeder automatically loads paper when you send
print data to the printer (as long as the PAUSE light is not on).
You can also load paper from the cut-sheet feeder by pressing
the LOAD/EJECT button.
Using Printer Options 4-9