[exim] routing to seemingly un-routeable address

/dev/rob0 wrote:

>>On Monday 2005-September-05 15:02, Jim Pazarena wrote:
>>
>>>>I have an issue cropping up with a domain name of:
>>>>
>>>> sk.sympatico.ca
>>>>
>>>>a user claims that it is a valid domain name for a friend of his, but
>>>>my mail server claims it to be un-routeable,
>>>>
>>
>>How so? What does it say?
>>
>>>>and indeed a "dig" doesn't produce much info.
>>>>
>>
>>It has SOA, and 2 NS records. No A nor MX.
>>
>>>>what happens with names such as these on mail servers which actually
>>>>_can_ route to it? how do they do it?
>>>>
>>
>>Perhaps it is a case of differing views for their clients. I'm unsure
>>what you are asking here. Do not confuse routing with resolution.
>>

I posted this question in a "bind" user group. Would appreciate an exim
response.

the question then, is,

SHOULD a mail transport agent accept an email addressed to this domain?
with no "A" or "MX"
how would it determine how to route it ?