Many times flamers (we know who you are) think nothing of wasting public resources, others' time, and polluting public forums with things best not said.
Since their statements are not strictly on the foul side of the moderation guidelines, IMO, they cannot be blocked from the list. In any case that's a dangerous trend.
So what do you and I do? Do we put up with their tasteless emails, do we allow them to spread their ill cheer to us across the pipes?
There is still something we can do.
It's called cold treatment.
Flamers are usually after recognition and attention. (Begin fictionalised quote) "I'm important! I can string a sentence together! I've been ignored all my life! YOU CAN'T IGNORE ME NO MORE! I CAN WIN TOO! YES I CAN! NO, REALLY! Here-- no, don't look away! Hey, LOOK AT ME! I have my worth, really! If you won't admire me, I'll FLAME YOU! I'm cool! I'm not worthless, I'm not, I'm not, I'm not! LOOOOOOK AT ME, WOOOOOAAAAAAH!" (End fictional quote)
Flamers usually self-destruct if we give them the cold treatment. This is well-known, though it takes time. Even hardened prisoners usually come quiet at the prospect of solitary confinement. These flamers aren't evil.
Let us isolate them. Let them shout their inanities to silence. They need a captive audience. But we refuse to be captive. Let us deny them the attention they crave, and watch them shrivel and shrink away.
All we need is to stick to it.