HP Officejet Pro 8600 - Manual (Page 29)

4. Pull out the extension on the output tray.
Load envelopes
To load envelopes
Use these instructions to load an envelope.
1.
Pull out Tray 1.
2. Insert the envelopes print-side down and load according to the graphic. Make
sure the stack of envelopes does not exceed the line marking in the tray.
NOTE: Do not load paper while the printer is printing.
Load media 25