I'm only logged in on one computer.  On the others, I just browse the publicly available areas.  There is still plenty to read there so it is conceivable that someone might register in anticipation of becoming an active poster but then just lurk for a while and not bother to login until something compels them to jump in and post.

But, I would bet that most forum registrations are bots.  That was the case when I had open registrations on my forums years ago and I'm sure it is even worse now.

For people that register and don't activate, on the registration success page, I would put up a notice that they will receive an activation eMail and they'll need to click that link to finalize their registration and that accounts not activated within 10 days will be deleted.  Then, information on how to contact you if they don't receive the activation eMail.  Of course, that's assuming you don't have something like that already.

I know that sometimes when I've had problems registering on a site, I might wait a day or so before contacting the site just because I get busy or whatever.  So, 7 or 10 days or something gives legitimate people trying to register a good amount of time to complete the activation or contact you.

Also, deleting incomplete registrations also prevents problems with people trying to register and then the system saying, well, you're already registered.  Or whatever.  I've had that too where I couldn't register because I didn't receive the activation eMail and then couldn't try again at a later date because the account I tried to set up was still there.

Also, there's a trend these days where people don't want to have contact with actual people, so having to send you an eMail to activate their account is going to be a no-go for them.

I used to lurk before posting on sites for a while. New writers can be bashful. But if you're able to see them not logging on, I'd think a year of not logging on is uninterested enough. Can they still re-join?

I'm thinking about a more pro-active delete if not logged in the first time within a day policy.

I'd give a week or two. I've been known to sign up for things but not get around to doing much with them initially.

Whatever policy you've had for spammers, it's working. That sure has decreased here since a year ago.

You don't need to be logged in to lurk, even though you can only lurk on 1/3 of the site. Some people are just shy, though I suppose the very shy wouldn't bother to register.

Good riddance. However, I'd give a new member a grace period to get acclimated before deleting them. A day is hardly sufficient time to browse through the posts, etc. Maybe a month? Newbies can be shy.

I'd be content with a service that a good method of detecting actually dangerous content, like virus masquerading as attachments. I can handle the rest myself.

I probably delete about 80% of what i get. Maybe more. But I'd like to make the choice myself. As I'm fond of saying, "The best spam filter in the world is the delete key."