I just received a reply from au@ua so I can confirm that it exists and is the address of a real person.
@Marc: it looks like Postfix is looking for an A-record for ua. If so this is a bug. RFC 5321 says there is no requirement for an A-record to exist if there is an MX-record for that domain*. This was unclear in the days of RFC 822 as the RFC predates the widespread acceptance of DNS.
"If one or more MX RRs are found for a given name, SMTP systems MUST
NOT utilize any address RRs associated with that name unless they are
located using the MX RRs" - RFC 5321 Section 5.1 (http://tools.ietf.org/html/rfc5321)
The TLD .io (British Indian Ocean Territory) has an MX record so somebody at the registry could give themselves a 4-letter address, e.g. a@io
If you have 1000AUD to spend then some Kiribati 3-letter domain names are available (e.g. 4.ki is available as I write) giving you the opportunity for a 6-letter address.
Shortest Email Address
I just received a reply from au@ua so I can confirm that it exists and is the address of a real person.
@Marc: it looks like Postfix is looking for an A-record for ua. If so this is a bug. RFC 5321 says there is no requirement for an A-record to exist if there is an MX-record for that domain*. This was unclear in the days of RFC 822 as the RFC predates the widespread acceptance of DNS.
Shortest Email Address
@Marc: I sent au@ua a test email today using eM Client on my PC (http://www.emclient.com/). Seemed to go OK even though I'm using a Google account.
Shortest Email Address
The TLD .io (British Indian Ocean Territory) has an MX record so somebody at the registry could give themselves a 4-letter address, e.g. a@io
If you have 1000AUD to spend then some Kiribati 3-letter domain names are available (e.g. 4.ki is available as I write) giving you the opportunity for a 6-letter address.
Go...