After importing several thousand issues from FogBugz, we noticed that some of the comments that were added to FogBugz via email were missing from the migrated issues. The Importer reported no errors regarding this. Since the issues themselves came through ok, along with all comments added via the web interface, it is difficult to say how many email comments didn't import successfully, but a small sample indicates that something in the neighborhood of 50% of email comments failed to import. We have yet to discern any pattern about which emails imported successfully, and which didn't. There are even a few issues with multiple comments from the same user, some of which imported successfully, and some of which didn't.