Exim or SMTP problem

Hi,

Does anyone know what to make of this:

-
Delivery attempt for Message ID 1GjCZP-0001uO-VP

Message 1GjCZP-0001uO-VP is not frozen
delivering 1GjCZP-0001uO-VP
Connecting to zuul.ihug.co.nz [203.109.252.44]:25 ... connected
LOG: MAIN
zuul.ihug.co.nz [203.109.252.44]: Connection reset by peer
LOG: MAIN
== <EMAIL_REMOVED_BY_ME>@ihug.co.nz R=lookuphost T=remote_smtp defer (104): Connection reset by peer: zuul.ihug.co.nz [203.109.252.44]
-

It only happens for @ihug.co.nz server. Emails sent to any other address work fine.

Thanks in advance,

Joel.