I use Earthlink Webmail, which is generally pretty good about filtering spam, and it allows me to block senders that I identify as sources of spam.
Most of the time...
Now I seem to have gotten on the radar of "cron-job.org" which sends me daily junk, and for which Earthlink indicates that "blocked sender" status is inapplicable. I can understand why such limitations are applied to sources at "hotmail" for example, but why would some entity like this be protected?
Addendum: A hat tip to reader BJ Nicholls for offering this link in his Comment. It explains that the legitimate cron-job site has had their address highjacked by spammers.
Since Earthlink wouldn't let me click to add this "contact@cron-job" to my Blocked Sender List, I've now done so manually. We'll see if that works.
Addendum #2 a week later: Manually adding the source to the Blocked Sender List seems to have worked - though I don't understand why Earthlink wouldn't let me just click to do it.
