This bug has been opened here: https://bugzilla.ubuntu.com/show_bug.cgi?id=17942

"Evolution(Breezy releas) is Set to check my mail every 1 minutes.  For the past
day and a half, every half hour or so, it fails to properly connect to the IMAP
server.  The progress bar on the 'check mail' dialog never moves anywhere.  It
fails to timeout at all either.  (sits there forever).  Using the cancel dims
the progress bar and the cancel button as if it's working, but it stays like
that indefinitely as well.  

The only way to get rid of that window is to use the window manager controls to
close it, (which works).  The interface of evolution still works.   However, the
only way I can get it to successfully check my mail is to quit all of the
evolution windows which are open, and then kill all evolution processes, and
restart it.  At which point it will succeed at checking my IMAP account for a
little while (< 30 minutes).  Then the cycle restarts.

I assume, but cannot verify, that the IMAP server/connection is having
hiccoughs.  In any case, it should timeout after a bit, and ultimately, it
should always properly 'cancel' when I select that option."