Epson 1010 User Manual page 69

0.12 inch
(3 mm) minimum
Note: Envelope printing is only available at normal temperature
(40°F to 95°F or 5°C to 35°C).
To make sure that the printing fits within the printable area, always
print a test sample using a normal sheet of paper before printing on
envelopes.
2-30 Paper Handling
0.33 inch
(8.5 mm) minimum
0.87 inch
(22.0 mm) minimum