2012/09/11 - IMAP Server tuning and maintenance
The University's email mailbox system (IMAP server) has been heavily overloaded during the third term which has led to very slow response times, especially during the morning (This noticeboard posting has more detail).

Last night we completed testing of, and brought online, a second mailbox server, and over the next two days we will start migrating approximately half the student mailboxes to it, starting with 1st year students (in fact all those who first enrolled this year and therefore have a student number beginning with 12), then 2nd year students and so on. As each mailbox is moved, it will seem to disappear temporarily - which will make your email client disconnect - and will then remain unavailable for up to five minutes depending on the number of folders and the amount of mail. These moves will be done mainly in the evening and overnight.

Due to the design of our IMAP infrastructure, there will be no visible change and no need to adjust the settings on mail clients; but this should improve response times (we're effectively doubling the back-end capacity of the IMAP system).
Note that the problem referred to above affects all mail clients trying to retrieve Rhodes email, including the webmail client at
The first migration - of students whose username begins g12 - is now complete, and with approximately 10% of all mailboxes now on a different server, early indications are that the instability in the email system has been significantly reduced.

We still have scope to balance the load further if this doesn't resolve the problems, and I've identified a couple of tuning issues on other systems which might have contributed and which I will be investigating further.