members.shaw.ca is sending .lha as "text/plain". That is a bit messy as the file will be delivered as text.
Dunno if you can fix this directly (I doubt it), but maybe you could ask the admin to fix lha/lzh/lzx mime types:
application/x-lha lha
application/x-lzh lzh
application/x-lzx lzx