Ditto. Now opening for ~3s before crashing. Possibly coincidence but began after marking all messages in an inbox category as read (there were tens of thousands).
[edit] logs forwarded
Mind sending the crash reports to bugs@mimestream.com? If you aren't sure where they are, just run /Applications/Mimestream.app/Contents/Resources/collectDiagnostics.sh in Terminal and that should zip them up into a file on your Desktop. Thanks!