I have checked and there is a Yahoo group "digital photography". I
joined the group but have not recieved any messages yet- do not know
how active it is. I will report after a few days.

I belong to a number of Yahoo groups, and moderate two.  There is
occasional spam that slips through.  Most groups are set up with
messages themselves NOT moderated, but require membership to join the
group and many moderate membership.  Sure, a "new member" occasionally
slips through and posts spam, but that member is then kicked out.
Someone could indeed keep rejoining under new names, but this has not
been a problem so far.

Yahoo groups allow you the choice of receiving posts via email, or
reading them from the group web site.  For really active groups there
is a digest version where the messages are bundled 25 at a time and
sent out.  However, for a group with as many posts as rpd, even that
may be impractical, and web reading may be the best solution. I have
selected the digest option for the digital photography group, and will
let this group know how that works out.