Due to a sequence of unfortunate events, triggered by a failing power supply over the holiday period, it came to the attention of the computing staff on January 1st that external email addressed to @inf.ed.ac.uk email addresses was being rejected and returned to the sender.
Though it was the holiday season, this was fixed at 7:45pm on January 1st. Investigation of the problem showed that from 9:22am on December 31st 2012 to 3:15pm January 1st (ie for some 30 hours) email connections from the outside world were being rejected. This resulted in the mail being returned to the sender and them being notified that their mail to @inf.ed.ac.uk had failed.
This probably shouldn’t be a problem for humans used to sending mail to @inf, as hopefully they’d (correctly) put this down to a temporary fault, and try again at a later date. Which if they did so after 3:15pm on the 1st, would work the second time around.
Slightly more problematic would be email from automated systems, eg mailing lists. However, usually they are reasonable too and will allow a few failures before taking any automated suspension or unsubscription action. This will depend on the automated system in question.
As the connections were immediately rejected by the mail server, we have no record of who the rejected email was for, or who it was from.
Given the time of year, it is hoped that not too much legitimate email was bounced during this period. If you’ve seen odd messages from friends or systems asking if your email was working over the holiday period, the above will probably explain why.
Needless to say we’ve made changes so that this particular sequence of events should not occur again.