I run mail servers for a number of businesses and also offer mail services for businesses so have mail servers out there.

Recently truck loads of spam from icu domains.

I wrote them an email this a.m. telling them I am considering banning any emails from any .icu domain and banning all emails containing links to website addresses ending in .icu.

Surprisingly got an answer where they say they are business people, who try to do a good job, and aren't black listed on black lists etc.

My response basically said that about 95% of all spam slipping my filters is from .icu email addresses and 0% of email from ,icu addresses is legitimate. It costs me time and money to deal with that spam so black listing all .icu domain emails makes good sense.

I did check spamhaus and a few others. .icu is not in the top 10 tlds for bad behavious but rate at 21% bad sites and have a score in the high 20's as a bad behaviours ranking domain prefix. By contrast .ru (another spam pitn) is 2.1% bad sites and ranks 0.6 score.

There used to be some great software called something like bluefrog, which had an add in for outlook and other mail clients. if a person marked an email as spam it told bluefrog which email it was and if  enough folks flagged the same email it was parsed, banned, and the links in the email were automatically used to post 1 form  reply, to who ever was spamming others, tellig them to stop spamming.

is there any good systems like this still around? Crowd sourced email spam reporting so that when it is marked as spam by 2-3 people it is banned as spam across all mail boxes that use this service?

Short of that banning top level domains makes sense if no legit email is coming from them and they keep sending spam. Banning .ru on one server, as all mail users let me know they had no legit contacts with any .ru mail addresses or businesses, rediced spam significantly.

Maybeif enough folks black list countries or sites causing spam grief get the message will get through that it is cutting ones own throat to allow spam and they will do something about it. Nigeria, Romainia, both high on my list. So is the netherlands and certain isps from USA.