That's a good idea. Now we've got junk solicitors putting up crap about 'miracle cures' and 'enhancement' products. I've been deleting and warning them, but they don't seem to care. Plus, it looks like they're making multiple accounts for the same person/people. :smt013
I think that's fine for inactivity purposes, but I think solicitors should be deleted quickly. Their purpose is quite clear and has nothing to do with this site.
Although I can't say I'm 'good' with phpbb, I can make a suggestion. I've been looking into this issue and found someone who made a bit of code to filter the bots by confusing them. Check it out here --->Spam Filter Code<---.
I've seen other possible options, but they seem a bit complex. I think simpler is best