On Fri, 3 Nov 2017, Don Hollander wrote:
The UASG will (after further consultation) include the following as a Good Practice (not best practice) guide for Downgrading:
- The EAI Mailbox provider establishes an EAI address and an ASCII alias when the mailbox is set up.
- The ASCII alias will have a display name equal to the EAI Address.
- When a non-EAI compliant mail system is encountered, the EAI MTA will revert with the ASCII alias and Display Name.
- The ASCII Alias should not default to a Punycode conversion of the mailbox name because bi-directional equivalence cannot be guaranteed.
Also note that only the initial sender can do this. If mail goes A->B->C, A can downgrade if the A->B hop can't do EAI, but B cannot if B->C can't. Regards, John Levine, john.levine@standcore.com Standcore LLC