I am curious to know if any sites have any policy about deleting old, inactive forum threads?
For example – one that hasn’t been added to, or viewed in two months maybe?
Would there be a good reason for leaving it up?

Well, I am just starting my User Forums, so no real experience yet in that direction. Seems to me, with other forums that I have worked with, that if no use of a thread in 2 months, it would be worthwhile to delete.

I'm trying to do a forum Rules and Guidelines, but just starting on that. I just renamed General instead as General and Guidelines, and put the guidelines anchored at the top. If I wanted a guideline that threads without activity in x months, I would disclose it there. I see no reason to retain unused stuff.

My 2 cent worth I don't post to a thread but go back and look for something that has been posted a long time ago.

I might remember someting that I could use on my web site.

Sure you have to look thru a lot of threads to find something but it is worth it.

I have left most of mine up. Often new people come in and kick a thread back into life.

I have deleted those that I considered a closed discussion like "Your Visualization of the Perfect Reunion" I had heard enough. I probably could have just changed it to read only.

We must remember those classmates who, alone, sleepless, and bored, in the middle of the night come on the sight looking for mental stimulation. They will read anything.