I am not sure if MHonArc has this functionality, but a nice little shell
script command to get around this is "touch". If you run MHonArc from a
shell script(or at or cron, whatever) you could throwin two(one) line
beforehand saying touch <htmldirectory>/maillist.html
Some browsers will have problems with empty files -- they should have a
tag to help things out.
My scripts that feed things into MHonArc automatically create the directories
as needed right before calling MHonArc, so I don't run into this problem.
Alternatively, you could create a template file that has the <body> tags
and copy that into place...