From a reply from Support:
On Wed, 08 Mar 2006, you wrote:
Looks like those messages were delayed on our load balanced mail servers.
Since this is really a new service there are likely some issues we need
to resolve. I have moved this request to my personal queue and I'm
sending the log information showing the delay to our administration team.
They will look into it and as soon as I have any information for you
I'll be happy to pass it along.