Envelope printing can be a challenge. Any free software I have tried is clutzy/clunky. If you simply want an easy way to throw in a quick cut and paste address, why not just use a nice .rtf envelope template from Jarte templates. Grab some lable templates while you are at it. Jarte is a great little stand alone word processor in it's own right so give it a try while you are at it.
In the printer settings chose layout as "landscape" and media as "envelope". LibreOffice does this fine on my Brother HL-5250. Of course all printers have their quirks and settings so some tweaking may be needed. The hard part is getting the printer, which needs to have the envelope fed vertically into the front, to format correctly.
All versions of Microsoft Word have a little envelope wizard which works like magic but we are trying to wean ourselves from MS Office are we not? And of course we can always print the address on a sheet of paper, cut out the address with a scissors and tape it to the envelope - anything to keep from hand writing the address, or am I the only one.
