I have had seen this issue with envelopes and sticker sheets, I had to get a Xerox technicain to adjust the fuser / print sensor / pressure of the print area. Forgot exactly what he called the area that he adjusted. Since then, haven't heard about the issue returning.
Thank you for using the Support Forum. Please take a look for the solutions for Jams or Misfeeds when Printing Envelopes. Also make sure you are following all the steps in the solution for Loading Envelopes. If these solutions do not help please consider contacting your support centre for further assistance.
I have a new Phaser 6510. I went to print my first envelopes in the bypass tray. Every time, the envelope will get caught in a paper jam at the back of the printer. And, when I retrieve the envelope, there is no printing on it and the back of the envelope is fused. I went to the settings in the print menu and set the printer to print envelopes. No different result. I really need to be able to print envelopes and other non-standard paper sizes. Any idea of what is going on and/or a solution?