As an addition on my previous comment: in order to get more/useful log information about the IMAP server communication, please start evolution using: env CAMEL_VERBOSE_DEBUG=1 evolution >& ~/evo.log
Also, it might be a solution to update to a newer version of evolution, the natty repositories provide version 2.32.2. Maybe this will fix your problem..?
As an addition on my previous comment: in order to get more/useful log information about the IMAP server communication, please start evolution using: env CAMEL_VERBOSE_ DEBUG=1 evolution >& ~/evo.log
Also, it might be a solution to update to a newer version of evolution, the natty repositories provide version 2.32.2. Maybe this will fix your problem..?