I don't believe this product is designed to handle #10 envelopes. see the link below which outlines paper trays and types
1: From Start>Settings>Printers and Faxes.
2 :Right click on XeroxD110 PCL6 & select Properties.
3: Select the Configuration tab. Select Custom Paper Size button.
4: Define the envelope size. For the short edge ,input 4.2 & for the long edge, input 9.5. Click the Named Paper Size box & name the paper # 10 envelope.
5: Select OK.
At printer load #10 envelope with the flap on bottom load Short Edge Feed in tray 5
From Word select Mailing tab then Envelopes type in address and select print.