It is best to mark just one spam post as abusive by each spammer, and not to delete. The forum admins have gotten much better. They ban the account, sometimes within minutes, which deletes all of their posts in all forums in bulk. If they don't deal
with it in an hour, I mark another post. They complained when I marked all of the spam posts as abusive, saying it confused them and they couldn't keep track.
Richard Mueller - MVP Enterprise Mobility (Identity and Access)