Some forums used to have a "block for a while" option, usually hours or days. But that dropped out of fashion for reasons I am not sure of - I suspect most use

Some forums used to have a "block for a while" option, usually hours or days. But that dropped out of fashion for reasons I am not sure of - I suspect most users discovered that actually it was just annoying to repeatedly re-block the same people. Stross blog has a user known as "the seagull" who creates new accounts frequently and spams vulgarity daily. She knows Stross personally and apparently he has decreed that she is allowed to do that. So a lot of his readers install plugins to suppress her comments... and have to regularly block new accounts that she creates (she has a very distinctive posting style)