Just a quick one about our recent upgrade - I had a full disk backup from an lvm snapshot to roll back to just in case.. all went pretty smoothly until the end when postfix wouldnt start due to a missing transport.db (we use a modified one which was overridden in the upgrade, but the postfix conf still looked for it - postmap sorted that out quickly). The only other issue was a default certificate replacing our commercial one, quickly sorted out with zmcertctl as well (PFY playing with certs about 6 months ago may well have started this). The upgrade took about 1 hour, which included consistency checking across +- 150 mailboxes.

Nice work guys, the only problems I had with the upgrade were self inflicted and the process was nicely logged and explained!