Werner Reisberger werner@pure.ch writes: ...
The only reason for this header lines could be to provide a standard way of using a mailing list. I think it's a futile effort. I don't know any mail reader making this header lines usable and most people don't even know what's a message header.
I hear that exmh provides menu items to subscribe, etc for lists that provide these headers.
As for it being futile, I don't think so, but I think it's definitely a _very_ long term project. They were standardized over two years ago, but that's a blink of the eye in mail standards: the first standard for internet mail messages was published as rfc724 in May 1977. It has taken over five years to revise the SMTP standard and rfc822 and they're still waiting for IESG approval.
Support for them will probably make it into the major MUAs some time in the next twenty years, so we might as well start supporting them now.
Philip Guenther Procmail Maintainer