I just migrated my email from evolution 3.2.3 to thunderbird. As that version of evolution is already storing email in maildir format I exported all folders by hand into mbox format (from within evolution, doing select all + save as) and then imported them in thunderbird with ImportExportTools. This has somehow caused a dramatic size increase of my mail archive. The evolution backup is only 0.5G and after exporting everything to mbox I now have 56G on my hands (so about a factor 100 increase). After importing everything into thunderbird it did not really get smaller. The two archives really contain the same data. Does anyone know how this is possible? I thought that maildir and mbox formats were more or less comparable in performance.