Belated thans again to all who helped me with this problem. It has been
running reasonably well since my last posting. I now have only a couple
of minor problems left, one of which (I think) more suited to the
postfix forum.
The other one is max-size. I had gradually uprated this to 8000000 in
the content filter .sh file, called via master.cf. I have tried setting
it in /etc/default/spamassassin as --max-size=8000000 (which accepts it
but ignores it) and in spamass-milter which does not accept either the
long or short version (which is expected from the docs).
Where should I specify this and how, please?
