Thanks for the suggestions Joe.
We don't have a tray 6 so that's not an option for us. Although, we have used tray 5 to print #10 envelopes successfully in the past.
I think you're right about the tapered flap being the source of the jamming, because plain paper cut to the same dimensions will print without problems. What we ended up doing was to create a plain paper insert that we stuff into the A6 with the flap open. The insert sticks out 1.5" making the length of the envelope+insert 8.5". We then tell the printer that the paper is 6.5" x 8.5" and it works. The problem is that stuffing and unstuffing 500 envelopes is going to be very labor intensive, which we didn't plan on when we accepted the job.
In the future we'll have to tell customers we can't print A6 envelopes with the equipment we have. :(
As far as I can tell the tray 5 can't run envelopes, so it would have no envelope option, so it can't expect the flap.
So if the flap is not squared, the printer would read the flap at the center, bot not the sides, this would leave the printer to believe the paper was not feeding straight, in which case it would stop the run and state it was jammed, but nothing would be damaged at all, the paper would be fine, just stopped, and near the entrance would be likely.
If that is the case, run it flap closed, and just get the GSM settings correct. Might be smarter to run as labels just to bring the fuser heat down a bit (less likely to affect the glue)
If you have the tray 6, there is an envelope device in the tray that can be placed to make it officially support envelope stock so you won't need to lie about what is loaded.
I need to print A6 envelopes (6.5" x 7" with flap open) on our Xerox-C75. I have to enter the paper size as custom (6.5" x 7") through tray 5. Every time I try to print, however, I get a paper jam error and the envelope gets stuck in the printer just before the fuser. I can print on smaller paper fine, but the A6 always jams.