Thoughts on Message-ID generation

[Toby Speight <streapadair@gmx.net>]

With all this talk on how to generate message-ID values and ensure
their uniqueness, it's long been my opinion that the Right Way to do
this is to have a well-known MessageId service.  Connect to the
assigned port on any server (perhaps even localhost), tell it how
many ids you want, read them in, and go away until you've used them
all.

Then it's the job of the issuing service to generate a unique
localpart for each id and a conformant rhs; uniqueness can be
ensured even amongst different clients (once all the ones in use
support the issuance protocol), one server can issue ids for an
entire domain, and offline working (and private networks) are
supported.