Yes, but if this is load borne by the recipient to service the publisher
...
It's not the cost (as such) that I would have a problem with - it's the
cost-shifting.
If it overall reduces the load, then it's shifting costs off the
receiver. It's not perfect since it doesn't put the cost on the sender,
but I think it's acceptable.
Remember that part of why email is so oft used is that it is cheap to
send -- that's why it's replacing phonecalls and faxes. You can only
shift the burden so far without making email only as useful as the
phone.
Ari