If you receive emails on the site which are harrassing or threatening, keep the emails in your default box and use the "block" function on the senders profile.
Inform the admin, Petrarca, via email of the incident and let him sort it out. There is no need to get everyone involved.
If it needs immediate attention, copy and paste to whichever mod is online at the time to consider a gag until Pet can deal with it.
As always, KEEP IT OUT of public chat.