Epson SQ-2550 User Manual page 74

If it is necessary to eject the printed envelope, press the
button to set the printer off line. Then press the
button.
CAUTION: When printing on envelopes, be sure that
your application program settings keep the printing
entirely within the printable area as shown below.
Printing on Special Paper
ON LINE
LOAD/EJECT
Paper Handling 2-29