I've been trying to use links2 to view html part of messages. 

The problem I'm encountering is that, the part would be saved as /tmp/xxx/xxx.shtml and

passed on to links2, and it seems links2 doesn't recognise the .shtml extension. 

netsurf works well with .shtml though. 

But being stubborn as I am, I would like to know if I can make notmuch output .html file instead? 

I did a bit of research on shtml, seems it's completely unnecessary in this case? why would notmuch choose this extension anyway?