You should organize a mailing list of old posters and send simple form letter invites for them to check in.
Be sure to include the URL, as many may have lost it over the years.

I did it on my board and it got a couple hits.

Couldn't hurt anyway. Does this system have a mass mailing to all registered posters feature?

I think so; I'm pretty sure I have, or can get, that feature ...
I'll have to delete the spammers though ...
Don't need them coming back; you know?

Lol yep, but I bet none of their emails addresses are still valid.

Uhm, the spammers, or the old users (or both)?

The spammers foo, they change their shit all the time.

Yeah, mostly randomly generated email addresses ....

... just a note, I installed an add-on that allowed me to do this recently
I just sent out the first batch of emails ... (I can only send out 250 at a time so I don't bog the server) ...

We'll see what happens ....
I've noticed a few more hits; we'll see if it gets any results ...