Labels is the one lock-in that stops me from migrating off Gmail/Google Apps. It is now what I insist on in a mail solution. Folders is just to inflexible for m

Labels is the one lock-in that stops me from migrating off Gmail/Google Apps. It is now what I insist on in a mail solution. Folders is just to inflexible for me these days as I auto label across multiple folders too much. Haven't really found alternatives for labels in other solutions. IMAP keywords is too restrictive etc.