[enum-wg] ENUM-capable email client?

* John C. Klensin:

> permitting, e.g., 
>    +12345678901234
> 
> as an email address would require changing of every MTA in the
> network before ENUM->email would work reliably.  Such agreement
> is unlikely.  For example, +12345678901234 at example.com could be
> a valid email address today, having nothing to do with ENUM.

You would use +12345678901234 at e164.arpa, I guess, where the @e164.arpa
part could be supplied by the MUA.  (Of course, e164.arpa should have
a "MX ." RR.)

If you opt for a purely MUA-based approach, you can never-ever put
E.164 addresses in the message header.  ENUM email addresses would
remain second-class citizens, just like internationalized domain names
implemented with IDNA.