[racbart]

Yup, my provider is quite easy to find, I don't mind. I just didn't want to make this info to be googleable with their name, to respect that they never publicly wrote about it.

No idea why they don't advertise this feature. They wrote that they only tell about it to people that are actually having a problem about it. I guess it might be easier for them or for other email-ops to handle abuse/spam issues when this header is available?