I was really bugged today as one of the new upgrades to Evolution broke my client completely and I was not able to use the email client early in the morning. So, I though of moving my emails to my secondary email client Thunderbird. All I needed to get this work done is a plugin called ImportExportTools (MboxImport enhanced) found at Kaosmos website.
Its awsome! I didn’t loose any emails and it was quick when compared to Evolution export and imports.