The previously posted issue was resolved at 4.10pm AEST (~ 40 minutes).  All mail in the queue was then delivered.

A conflict appeared during a software update to the systems used for the spam and virus scanning.  These updates are applied routinely every night, unfortunately this particular one didn’t function correctly.  We appreciate your patience and understanding.

There’s currently a delay of all mail being delivered on both astro and atom.  The issue will be resolved shortly and all mail will be delivered.  No email messages have been lost.