I haven't seen a printer that can't handle an envelope in years. Generally they're fed in from the back, top "tray" if the printer has one and you just slide the guides in to the correct width. If it doesn't then the same thing can be done with the regular tray with the guides adjusted.
Brian - Virginia, USA - Windows 10, 64-Bit, Version 22H2, Build 19045
If you cannot or will not imagine the results of your actions, there’s no way you can act morally or responsibly. Little kids can’t do it; babies are morally monsters — completely greedy. Their imagination has to be trained into foresight and empathy.
~ Ursula LeGuin, 2005 Interview in The Guardian