I was able to get libreoffice to generate a nice landscape #10 envelope which I exported to a *pdf.
Libreoffice -> lowriter ->
File ->
Text Document -> F
ormat ->
Page.
Choose landscape and #10 envelope. You can also adjust margins
I then added my text fields along with a small lineart image and exported to pdf.
To print open the pdf in
textproc/xpdf and print to the envelope printcap entry.
I have about 3 monthly mailings although I would like to learn
print/Lyx this is good for now.