A teergrube is a mail server designed to trap spammers by tying up their computer resources. The term comes from the German word meaning "tar pit." The teergrube's owner sets the trap by placing phony email addresses where address harvesters will find them on Web pages. The owner also includes a warning not to send email to those addresses. Humans will see it but automated harvesters can't. When a spammer sends email to the trap addresses, the teergrube accepts them but only very slowly, which ties up the spammer's computer. The owner can configure the teergrube to keep its connection open for extended periods, which allows the owner to trace the message back to its source.

Teergrube is German for "tar pit". In internet terms, a teergrube is a system that acts as a tar pit for spammers -- causing their internet connection to become stuck or to slow down dramatically.