Epson Stylus Photo 825 Printer Basics Manual page 43

Set the thickness lever to the + position. (Remember to move the thickness lever back
to the position when you're done printing envelopes.)
0
Load with the
printable side up
Before you print, make sure you choose the correct envelope size as the paper
(Windows) or
Paper Size
(Macintosh OS 8.6 to 9.x), or page 42 (Macintosh OS X).
(Macintosh) setting. See page 39 (Windows), page 40
Set the
thickness lever
+
to the position
Printing From Windows or a Mac
Size
37