[anti-abuse-wg] Non-ASCII characters in abuse-mailbox addresses

Hi,

some abuse contacts registered with RIPE use non-ascii characters with
the abuse-mailbox addresses, e.g.

% Abuse contact for '195.78.76.0 - 195.78.77.255' is 'abuse at zürich.email'

However, the corresponding MTA does not support SMTPUTF8:

7B579403C6: to=<abuse at zürich.email>,
relay=mail.xn--zrich-kva.email[109.95.241.50]:25, delay=0.33,
delays=0.01/0/0.32/0, dsn=5.6.7, status=bounced (SMTPUTF8 is required, but was
not offered by host mail.xn--zrich-kva.email[109.95.241.50])

(In this particular case, sending email to the IDNA representation of the
email address <abuse at xn--zrich-kva.email> works.)

In our experience, using umlauts and other non-ascii characters in
(the host part of) email addresses still cause a lot of problems in general.
Even if the recipient's MX supports SMTPUTF8 correctly, MTAs on the transport
way may fail to handle SMTPUTF8 messages.

To prevent such problems and make sure all abuse mailboxes can be addressed,
I wonder if the values of abuse-mailbox attributes should be restricted to
ASCII characters only.

What do you think?


     - Thomas