Lexmark MS812dn / MS812dtn
Open the rear mailbox door.
Remove the jammed paper.
Note: Make sure that all paper fragments are removed.
Close the door.
If the jam is in the mailbox bin, then remove the jammed paper.
If necessary, press on the control panel.
The printer posts a paper jam error with the paper stopping at the rear door. See this article for troubleshooting steps.
Troubleshooting a 202.05 Paper Jam