Non-compatible paper, Only one-sided printing is possible, Use as soon as possible after opening the package – Ricoh BY1000 User Manual

Page 30: Up to 20 envelopes can be loaded in tray 1, If the envelopes bulge, flatten them, Use tray 1 to load paper lighter than 157 g/m, 6 lb.), You can insert paper with weights up to 255 g/m, 0 lb.) into the bypass tray, Wrinkled, folded, or damaged