Sometimes some spammers get folk's emails and use those as proxies.
But not in the PM area.

PM's have been used lately, I guess for about 2-4 years now.
They are rarely spammed.
But it does happen.
I ban the isp number and that takes care of most issues.
About once every 2 years.
I have 6 folks that have been banned on this site.

Which if you look at the volume and google ratings, and compare that to other forum sites, I know is far lower. This place is very well behaved. It's almost beyond belief.

Regards,
Tom Barr