Epson SQ-2550 User Manual page 159

The Cut Sheet Feeder
4. Take a stack of envelopes and fan it; then tap the stack on a
flap surface to even it up. Insert the envelopes into the
front bin. (You can stack up to 25 standard envelopes into
bin. See the printer specifications section for more
the
information.)
Press the button to load an envelope. Then
5. LOAD/EJECT
press the button to start printing.
ON LINE
5-12 Using Printer Options