The likelyhood of "a significant population of SME Servers with out of date virus protection" is nil based on comment #6 and comment #7
Comments 6 & 7 Hadnt been posted at the time I posted.
Please do not jump to wrong conclusions and alarm users...
If you care to read carefully what I pasted in the bug report from just one machine, it was ignoring all the mirrors. I found four more servers doing the same. The message is not really abiguous, ALL THE MIRRORS ARE BEING IGNORED.
I would suggest very strongly, if the mirrors are being ignored, then updates are not happening and for how long has this been happening - since the update ! I think this is very alarming.