We have been informed that next Tuesday (8 May) between 7am and 9am, the OUCS Nexus team will be renewing (and changing) its security certificates. When they do this there will be brief interruption in the email service which could last for a few seconds to one or two minutes.
Nexus Team testing has shown that most clients will accept the change silently or with one user prompt in some cases as the new certificates (Comodo AddTrust) are already widely trusted. However, they have seen some hand-held devices taking some time to change to the new certificate, despite the fact that it is already installed and trust should be in place.
If your hand-held device does not automatically recover from this change over then please re-start your device and wait for 3 hours before contacting the OUCS Help Centre as the alerts/error messages take a while to disappear on their own.
Please see the following web page for further information:
http://www.oucs.ox.ac.uk/nexus/upgrade/certrenewal.xml