[Exim] Logging Commands in User Filters

I guess the logging commands don't work in user filters? That's
unfortunate because I have a filter that's really a system filter - but
I'm using it further down the pipe so I can get the envelope information
with the message and log that too.

So - if there isn't any way to do this I'd like to request a feature to
turn this on - as well as ALL system filtering features in "user"
filters.